Well, im having basically the same issue with 2 droids.. Wireless (and wired i believe) tether are giving me some issues, basically being slow, not loading etc. Lots of times when i look at the signal, both the up and down arrows are showing. I think i remember seeing the png for that labeled as throttle? So, when both arrows are showing, is it actually throttling data? That's how it seems to act a lot of times anyway..
I'm on the newest baseband, BB 0.4. Have re-activated and updated roaming several times. It seems like this used to not be an issue, but im having similar issues on a BB0.4 phone and BB 1.1 phone.. any ideas?