It's weird...do an image search for CAAD10 and some of them with 17 deg stems look great...and some look like the front end is drooping (like the evo you posted).
I suspect that it's due to the top tube angle staying relatively similar but the head tube angle decreasing for smaller sizes meaning the stem gets brought up and becomes less droopy
My old colleague found that the -12 Bontrager stem is a perfect angle on the CAAD10, match the slop quite well (BTW the red is BRIGHT, Picture really doesn't do justice at how bright it is).
-6 looks better, but -17 doesn't look too bad, gives quite an aggressive look