It should switch from 3G to 1X when sending or recieving sms msgs,but it should only switch to 1x while sending & recieving sms msgs for 1-3 seconds per msg at most,then switch back to 3G after sending or recieving the msg.If your Evo is not switching back to 3G then that is a problem.Try a full wipe,if that doesnt work maybe ur rom download has a bug/glitch. My Evo,runnin MikG 2.15 Sense 2.1/3.0 with a few tweaks of my own, swithes from 3G to 1x for a second or two while sending/recieving sms,text,msgs,but it always switches back to 3G immediately. I think that my evo got stuck on 1x,dont know why,only one time in the past 4-6months. I just restarted my Evo & it went back to normal. Wish i had more info for u,but ive never had the problem,so i dont even know where to begin really.Usally,if the rom is good,a complete dalvik,data,cache wipe will solve most issues.Good luck.