Greg-
Long day yesterday ... but fun. Bell to bell on the slopes - cold but bluebird skies and unlimited visibility for as far as the eye could see. Very few people.
Couple of points that I wanted to make about the EA90SL. The link I posted suggests that Easton was willing to provide replacement hub bodies for the too tightly machined hub bodies that only accepted DA cassettes. If they followed through with that offer (or are willing to), then maybe that puts the SLs back on the table for you? With the SLs you should get Eastons best bearing for the R4 hubset. I was misinterpreting your post to mean the wheelset was custom built with Shimano DA hubs.
The spoke count of the EA90 TT is kind of low for a bombproof wheelset. Sapim are very good spokes - the CX-rays having a higher tested duty cycle than the standard CX spokes. I suspect since the spokes aren't identified as CX-rays, but "aero" that they are not the rays. Something worth considering with a 16/20 count for all around use. Not saying it would be a problem ... just rambling thoughts. For reference, I'm rolling with 18/24 cx-rays on carbon/alu clinchers without any problems so far, but I do take some precautions with the carbon wheels as I mentioned before. The most challenging environment is group riding where it can sometimes be difficult to see what gotchas lurk ahead.
Since part of your goal is a race wheelset, reducing rolling resistance and aerodynamics are important. For me it was ride quality, rolling resistance, and then aero. The 32mm section depth isn't as aero as what some of your competitors are probably running - especially TT. That said, there are now theories being published that deep section wheels really aren't worth much of an aero advantage. So, who are you going to believe? 🙂 From my own seat-of-the-pants assessment, the 404s seemed to be more aero than the 303s when I demoed them. Mental or real, my demo rides weren't controlled enough to be anything more than gut feel.
So all in all, the EA90s should be an improvement over what you have now. But for race purposes you may want to think about what performance spec(s) is most important to limit any competitive advantage that you're seeing in key competitor's equipment. Again, it might be worth demoing and experiencing different section depths and other characteristics if you can, just to see what feels best to you.
As far as negative reviews, my experience in product management and marketing has always been that people who have a negative experience are far more inclined to write about it than those who don't. As long as there are just a few negatives mixed in with generally good reviews, it isn't likely that there is a systemic problem ... probably more application specific.
Tough decisions, I know. Good luck!
Mark