I've just gone from an 8310 Curve to a 9000 Bold and I much prefer the keyboard on the 8310. The keys are separate entities and I find I could type much faster on the Curve than I can on the Bold. The Bold feels smaller because it's slightly thinner but it's actually fractionally larger both in height and width.
I'd like my Bold to have the Curve keyboard. It's far easier to hit the wrong key now.
I was stuck between the two but went with the curve in the end due to ram, camera, size and also keypad. I much prefer the curve pad the buttons seemed a lot easier to press and I was much more accurate on it. 2G is so slow though! They really need to release a 3G curve.