In order to flash the ESPRIMG, you have to have root. Did you do the straight OTA or did you grab the OTA with root off of XDA? If you grabbed the original OTA, time to deal with loop and spoof again then flash the ENG build. After that, flash the radio from the OTA and then onto CM6.
CM6 is working perfectly for me. In hindsight, Eugene's MR1v4 was not very good. I along with others had some issues with sync where it would be syncing all the time. Didn't have this problem for the first week I had it on, but it stayed after that first week. I could get 18-20 hours out of my battery before the sync issues cropped up, then it would be a struggle to get 15. I also had to do apps2ext because the size of /data ballooned. Before I flashed CM6, the size of /data was 60 MB. That was with a 512 MB EXT3 partition. On stock, I sat at 115 and had nearly the same app loadout as I had on MR1v4.