Not sure about your application (the big trick is finding a compactflash to serial interface), but when I had a sharp zaurus I absolutley loved it.
If you don't like the built in distro, you can flash it with openzaurus. Its based off of debian and looks prety as all heck, and will even run X windows if you need it. I mostly use it for the terminal. That is unitil I tried to flash the origional sharp rom back on it, the sharp rom installer works like **** and it foobared my unit
I have an Ipaq h2210. Familiar runs on it fine. I use GPE. A nice feature about the hardware is the compact flash and SDIO port. You can get a pretty large CF card and a good SDIO wifi adapter and you'll have a nice PDA/Email/MP3 tool.