I used the Stealth 50 with cadence/speed/heart rate sensors from last Fall until two months ago.
I really wanted to like the computer and sensor. The hardware was not typical Cateye...top notch and a bargain price. My hardware failed almost immediately after purchase. It did look good on the bike, it is easy to read at speed and screen changes are fast and intuitive. Setting up the Stealth is not all that intuitive and the user manual sucks (to be fair, Garmin's user manual sucks equally badly).
Sadly, the firmware and software sucked. I had great difficulty getting the ride data off the computer and uploaded to the Cateye Atlas website...when it finally worked on the sixth or seventh of twentieth try at getting the data off the computer head and onto the website my cussing subsided to merely hurling invectives at the software team that wrote that crappy code.
Cateye customer service gave me a second, free computer head and also a free heart rate strap when they finally failed. They did so willingly and with a smile, fully aware they had a problem child product on their hands. Great customer service...backing up a poorly designed product that was, perhaps, rushed to market?
Although the second, freebie units were holding up well the glitches in the firmware got to be too much to deal with.
The Cateye Sync software program that uploaded to Cateye Atlas has the very much appreciated feature of uploading ride file data directly to STRAVA and Training Peaks. Garmin's 'Garmin Express' software that is used for device firmware updates and can be used to upload ride file data to Garmin Connect website really needs to add these options. It's a time saver to have and avoids exporting a file in GPX/TCX/FIT formats to then upload to Map My Ride, STRAVA, etc.
Meanwhile, Garmin prices kept dropping and I bought a ended up buying a 510 to replace the frustrating Stealth 50. The Garmin has been reliable, easier to use and has more functions (which you may or may not want/need, but I like them). The 510 is highly configurable to suit individual preferences for displays of data. You can display up to seven data fields per screen with 5+ screens of data available. Overkill or not, you CAN make those screens display exactly what you want to see and in the format/size that pleases you.
The backlight/night screen display on the Garmin 510 is better than the Stealth 50, but I never had difficulty with reading the Stealth in bright daylight or at dusk/dark.
The Garmin 510, despite some internet negative reviews, is light years better than the Stealth in almost every respect IMO. The only feature I can't find on it that I would like to have 'back' (that was on many of my older computers) is the up/down pace arrow. The 510 does incorporate a air temperature sensor and it seems to be pretty accurate.
The only other negative I can say about the 510 is the rubber plug that covers the proprietary cable connector's data port. I can guarantee you it is not waterproof or even very water resistant. Of course, how water tight is any electronic device? I bag mine when I get caught out in heavy weather any ways, so it's not a deal breaker for my use. Oh yeah...screen changes are just a bit slower than I like. No biggee as I usually only switch between my main data screen (speed/distance/elapsed time, heart rate, cadence, etc.) and my altitude/climbing screen.
I bought the 'bundle' deal and it comes with all the sensors stem/handlebar mount and a Garmin branded 'out-in-front' Barfly style mount. Price on the 510 bundle are down to just about $300. Last Fall the Cateye rig with sensors/strap ran around $225. Garmin 500's are priced at fire sale prices, if you shop around and find a dealer trying to close them out.
I'll use the old Stealth on my indoor training bike this winter.
My advice? Either buy a Garmin 500, which is now priced almost the same as the Cateye unit or go with the 510. The 500 is considered a rock-solid unit and offers almost every feature of the 510 except the 'cool kid' touch screen (when did buttons become obsolete and why, then, does the 510 still have three of them???) and Blue Tooth phone sync feature to brag about your ride to your equally connected friends 'in real time' or do things...I'm too old to figure out how to do or 'why' I want to do that anyway!
I also have a 510 that I bought last summer with my new bike. Here's a couple of questions for you.
Do you have difficulties uploading to garminconnect.com? Honestly, it's the worst consumer website I've ever encountered. Completely non-intuitive, especially since they've gone to the new "modern" version, and support is non-existent. There's even a forum that garmin has on the site and when you get there, all kinds of "known problems" that no on seems to respond to with answers.
I love the unit and its capabilities but everything else about it turns me off. Are you, or anyone else, suffering from this, too? (I'm trying to determine if it's pilot error on my part.) I yearn for answers.
My uploads to Garmin Connect have been 100% reliable. Garmin Connect is not the fastest website on my Somalian DSL connection, but then neither is STRAVA, Map My Ride, Cateye Atlas, Training Peaks, etc. They all are sluggish. The actual uploads and file conversion/exporting is pretty fast as is the ride editor in Garmin Connect.
I continue to use the 'classic' (older) version of the website. I agree that that new version is less easy to use. Maybe that's because I'm an <ahem!> older dude and prefer text-driven menus and commands to Egyptian Hieroglyphs cave wall pictograms icon-driven websites.
Cateye customer support was very good to me. Seriously, they were outstanding. They sent me replacement units for my failed hardware quickly and with an apology for the failures. Unfortunately, they never did figure out why both of my computers had difficulty getting the ride file data off the Stealth 50 units via the Cateye Sync software program.
The one change I noticed after the Garmin 3.20 firmware update was that saving a ride really does take noticeably more time. Saves used to take maybe 5 seconds (guessing here) and now they take about 30 seconds or so.
I have not had to use Garmin's customer support yet (crosses fingers!).
The Garmin forum was very helpful when it came time to update the 510's firmware to the new version 3.20. I had to delete the language files, temporarily, from the 510 to free up enough memory to do the upgrade. This was kind of weird...memory space is cheap and Garmin didn't build enough memory into the 510 to do a firmware update? WTH is up with THAT?
I also agree that the Garmin forum is chock full of bitching and complaining and that at least some of that is definitely valid complaints.
Getting back to the Stealth 50 unit, a training partner bought his Stealth a week before I bought mine. He still uses his and has despite riding almost daily has not had to delete a single ride (plenty of memory and his unit is almost a year old). He also received a replacement computer head unit as his first one was a POS that he could not get ride data off.
He is satisfied with his Stealth and has no plans to 'Go Garmin'.
His buddy (another guy that trains with our group) bought a highly discounted Garmin 500 and that guy loves him some Garmin! He's totally satisfied with the $159 Garmin 500. He was using an iPhone with apps prior to going to the Garmin 500 (just for comparison).
Based on his recommendation and other online recommendations I would have bought a 500 for my own use had not the 510 dropped so much in price.
I still want map functions and route planning so I'm going to get an 810 or 1000 when prices come down even more.