In July, I switched from my beloved Audiovox SMT5600 to a Blackberry 8700g. Part of the reason for the switch is that I wanted EDGE and I wanted a keyboard, but I wasn't happy with the phones out at the time on either GSM network here. I bought my slightly-used 8700 off a friend for a very reasonable price.
I haven't written much about it here because I really didn't expect to be using it very long - but overall, my experience with that device has been very positive. The Blackberry just works, and as anyone who has ever used a Blackberry in the past knows, RIM has really nailed the one-handed clickwheel operation (something I've heard many complaints about with the Motorola Q).
The other thing I learned is that I really like having a QWERTY keyboard. The 8700g is a bit clunky for my tastes, but it's a nice device and I can't imagine going back to a standard keypad. I've also tried the "split" keys on the Pearl recently and thought that was even worse than a standard keypad - though I assume you'd eventually get used to it.
Unfortunately, the Blackberry has also introduced a leak in my system, and as a result I'm going to have to replace it.
Like many of you, I have two distinct environments - work and home - which translates to two different inboxes. I process mail at work and create tasks and calendar items, but they're not synchronized with my home system.
This was perhaps the biggest selling point for me on the SMT5600. For all its problems, ActiveSync does a pretty good job of bridging that gap. Unfortunately, I can't seem to do this with the Blackberry. I guess this is in part a classic tradeoff between a highly integrated solution and a flexible solution. The Blackberry is the former, and it "just works" because it's tied to a single server. 
I'm thinking about picking up a T-Mobile Dash when they are released next week, which Ryan called "the slim Smartphone perfected". Dave said it is "definitely a Motorola Q killer" and went so far as to call it "the best Windows Mobile Smartphone ever to hit the market" - and he was using a pre-production unit!
Before I do buy this, I need to confirm with my HTC Universal that Windows Mobile 5 can handle the synchronization with 2 servers. I have a bad feeling I may need to turn off Direct Push e-mail, and that's not a reasonable solution.
But hopefully the Dash can plug the leak, because it's a very nice looking device.