yeah, some years ago I made a "impulse" tablet purchase too... the 12" cintiq was on sale for €800 since it became EOL product - it's just sitting in a box and my old Graphire 4 classic is still in use since my desk is too little to fit it on there together with all the monitors, keyboard, mouse and other usb gadgets.
(I guess this is meant to be a warning to others: Don't buy something expensive unless you're sure it's going to be used too! It sure is shiny though...)
Good news is I bough the material to build a new desk, just need to get around to finishing it too. :p
The idea of a wireless tablet is certainly an interesting one though. Hope you get it working 100% of the time and report back. :)
edit: one quick extra thought: is it 'failing' as a wireless tablet when the battery is low-ish?