So I guess the unofficial Froyo roms didn't fix the GPS since you are having the same crappy performance issues.
I'm waiting and waiting and waiting for the official Froyo update (if it ever comes).
Voice commands are no problem.
The close together roads are exactly the problem I have. In my neighborhood the damn thing jumps around to streets like Oprah jumping on a sale at KFC. Pisses me off. My wife's Garminfone and our Garmin GPS is deadly accurate on these same roads. I know they were more meant for GPS but damn can't this phone at least stick to the road you are on? I haven't ever used another phone with google maps so not sure if it's Google Navigation causing this or not. I guess I could try using Google Navigation on my wife's Garminfone to test out that theory.