I don't know about the Nextel BBs, but Nextel's Motorola handsets have notoriously loud ringers. If ringer volume is at all important to you, the Curve is probably a better choice. At least it was with Verizon, when I switched from my Nextel i580.
I have also seen people who have upgraded their BB OS complaining about significantly reduced volume following the upgrade, but I don't know if that was particular to one model or another, or a general issue.
if you like your current keyboard, the suretype, just go with the pearl. I had a 7100i and loved the suretype, but I love the real keyboard of the 8330 much more, so maybe you should try it. BTW, if you like having Nextel and it gives you good service, you could wait and get the 8350 that's coming out (basically the curve for Nextel). The only thing that stinks is that it uses Nextel's data network, which is slow compared to Sprint's, but it has wi-fi built in, though.
you could always try one phone under the 30 day return policy, and if you don't like it, swap it. But you can only do it once, so make sure you will like your second choice.
Help switching from Nextel to Sprint, What to choose?
