Never been on the east coast, but I ride similar mountains here (Big Bear, Mt High). The Evo is fine for that.
I rode the Evo at Loveland and Breckenridge. It was fine but when pushed it did chatter. I'll leave the HD stuff to those who actually ride it, but I'd be very impressed if they stopped the chatter.
Honestly, what was it about the SL you didn't like?
I jumped on a Coda and so far it's the most fun I've been on (which includes the SL and Evo). Jury is out on the Cobra as I've only had a couple days in Seattle on it. I need to take it to Mammoth to really know.
I'm not swaying you away from the Proto. I'd love to jump on one to try. Trying to get my buddy to buy one so we can swap Cobra/Proto whenever we want.
Honestly, I love my SL, just thought the blunted tips, more pop, and true twin would be a better fit for me. I love hitting all the natural features on my little hill here, but you can only do that so much before you get bored here. An average run here takes 30 seconds with a 5 minute lift ride. I'm just torn as whether to get something I can butter and press a little easier than my SL