What are you going to do with it? Will UMTS be available?
The difference between a JASJAR and an SP5m is night and day. If you are thinking about switching to smartphone, you have to write down the applications that are very important to you. Then see if you can get the same functionality from the smartphone os.
I've owned a pda2k, e-ten m500, mpx220 and a JASJAR. The JASJAR rocks and I liked the mpx220 a lot, but the applications are no where near as powerful. You may be very disappointed.