I agree with ZRunner. I suggest getting the Curve from T-Mobile and having it unlocked. RIM should be able to provide you an unlock code over the phone and at no cost as you will end up purchasing the device from T-Mobile at list price (I have previous experience with this).
Not sure how long you have used the 8820 but I would give it the free 30-day trial as offered by Cingular/AT&T.
I use used to feel the same about the keyboard on my 8800 (now 8820) but have grown to like it. I have to agree that I prefer the keyboard on my wife's 8300.