Xda IIi
I've operated an O2 Xda IIi pocket PC for over a year.
Seems to work tolerably well. Has frozen occasionally requiring soft reset but no loss of data.
Has WiFi, Bluetooth, GPRS.
Irritating that (unlike Psion) Pocket Excel cannot produce graphs and display isn't as appropriate for spreadsheet as Psion either.
Personally I'd like to try a Palm and the Nokia which looks like a Psion for comparison.