If all you do is basic PDA things like contacts, appointments, todo list, & email. It really doesnt' matter what smartphone you use and the Blackberry is good at that.
If you want to expand your PDA abilities to other things like mapping, eBooks, MP3 Player, Video and the hundreds of other things they can do, then a Palm or Pocket PC based smartphone makes a lot more sence. Since you like palm and since palm isn't broke there isnt' a problem with the direction you are heading.
The only one I'd avoid in that latter case is Symbian. They have implemented some kind of validation before a program can be run and that would rule out the vast majority of the kinds of applications that I use on my PDA that make it helpful.
I'm thinking of upgrading to a Treo 680, I currently have a BlackBerry. Was wondering what you BOLers out there have to say, if there is something else I should consider. I personally like the Palm OS vs. Windows Mobile. If you have suggestions, please let me know. It would be a great help in making my decision.