Along with those questions do you need a new by within a specific time frame?
There are some newer BlackBerries coming out that are worth waiting for, and some are alreday out. Bold/ Curve 8900/Storm, which offer a much faster processor and alot more memory then the previous BlackBerries.
8830 -> 8330 -> 9550 -> 9650
Just think about how far BlackBerries have come from then till now... And what else is coming.
The latest out right now are the 9000 Bold and the 8900 Curve. They're both quite a lot faster than previous models, both offer wifi, GPS, and full QWERTY. Basic difference between the two is that the 9000 offers 3G where as 8900 does not. The size of the 8900 is however smaller and if size is part of your consideration then that might be something worth looking into.
Best bet is go to a Rogers store and try both of them out. You'll be able to gauge which one feels better to you and is easier for you to type on and good fit in terms of size.
-Size (Bold is bigger)
-Speed (Bold is slightly faster.... probably not noticeable though)
-Camera (Curve has 3.2MP)
-Screen (Curve is slightly smaller but higher resolution)
-Price (Bold is higher in price)
There are other differences.... just search and you'll find them all.