I made the jump to 2.0 last night. After a while I experienced the same problems. 3g would drop out, 1x would be about the best I could get, and the browser was very slow.
That said, I immediately blamed it on UKB as that was about the only variable that had changed. The correspondence of the dropout and new ROM suggested it. HOWEVER, I got my wife's stock ED01 Fascinate and ran some side by side tests with loading web pages. She was having IDENTICAL problems with her signal (3G cutout, 1x etc), and our page loading was nearly identical on average.
This morning, on the way to work, I listen to Pandora in the car, and after getting about 5 minutes down the highway, I had full bars of 3g with no dropout.
For the ROM to interrupt the 3G signal, TSM would have had to change the way the ROM interfaces with the radio, of which I don't believe they did or would, as that would have been mentioned in the changelog.
Just my addition. I am comfortable with UKB 2.0 knowing this is MOST definitely a VZW issue. I too was about to restore my nandroid and head back to 1.3....