No, I dont think so about the alltel question. I have used my Samsung i760 and i730 (along with pdanet) for many years in the same location without the problem, and as mentioned my wife's usb727 verizon pc modem also works fine. Not very fast, and not a great signal, but not near the issues as with the Droid.
It is a very strange issue. The phone will show 3G with 3bars but then when you go to actually use data, it goes terribly slow, bars drop, or it may switch to 1x or may just give a "No network" error. I try again and it connects but is pretty slow. Then on rare occasion, from the same spot with the same bars (not that the bars seem to mean much) it works fine. My wife also has a droid and it acts the same way. Since the old phones worked fine I have to believe it is an issue with the Droid. Hopefully it is fixable in a future update.
Forcing it to "EVDO only" seems to help in one area of my house but in others can lead to "no network". And when in EVDO only there is no phone (cdma) network so you cant get calls. But this is what I do if I need to use it with Pdanet. The 1x is so slow it is pretty much unusable.
Telstar.