I have a GSM Treo 650, and migrated from a Treo 600.

As to devices, I still have an HP Jornada 720c hpc, which replaced a Jornada 680. Before the Treo 600, I had a GSM Treo 270, a blue Palm Vx with the bluetooth sled, (and a Sony ericsson T39m for connectivity) a Palm Vx with an Omnisky modem, a Casio Cassiopea 1st gen Windows CE device (FREE from Microsoft! It also came with a plane flight to Seattle, lodging, food, MS tours and tons of neat stuff), Palm 1000, and the devices that started it all, an HPC 41cx handheld programmable calculator with all the accessories, and an HP41cv. The HP 41cx became my first PDA, when I used its assembly language to write a PIM for it... five years before Jeff Hawkins invented the Palm!