Same here. I have an Evo on Cricket including market and apps except for MMS. The autostart/u2nl method for the Eris works on the Evo using the same autostart.sh script (unmodified). However the 3G connection is flaky and times out frequently. Also I get random Data Call error 98 messages related to Sprint stuff still on the phone. (I'm running a rooted stock 2.1 ROM)
I also noticed that during the toast root process I was able to ##778# (quite to my surprise) then it went away when I flashed the whitslack update ROM (upgrades radio, wimax, etc).
The strange thing re: MMS is that I tried the APN backup/restore option which worked on the Eris and it "appears" to work. The configuration settings within the Message application "look" right for Production but alas I still cannot receive or send pic messages. No biggie (I ain't paying someone just to get MMS working) but would be nice to have it working. Seems like overkill to have to create an entire ROM just to get MMS working.
Anyway...it's quite frustrating since the Eris works perfectly on Cricket with the autostart/u2nl solution.