My first bike ever was the Performance Focus, fully loaded with Shimano Ultegra 8sp STI. The STI lever broke, twice and finally when I called SHIMANO to find out about a replacement part? They told me it's no longe made.......
Rep told me to head to eBay to get a replacement one but.....I said: The heck with this I'm getting all Dura Ace and a new bike, the rest is history.
Anyhow, I bout a 2004 bike in 2007, all with DA 9sp and now the (left) STI shifter has a piece that's broken but nonetheless, the shifter works fine, I just don't like that little (looks like a washer on the outside of the mechanism) piece moving around everything I shift (using the entire lever to go up).
I've only had Shimano drive train and all I can say is that the rest of the parts have worked and last for a long time, except the STI lever, which I'm not to happy with 'em. But I'll upgrade to DA 10sp soon.