I bought mine a couple of months ago but have not had time to learn
even the basics, beyond convincing myself that typing all 26 letters of
the alphabet was at least possible.
I think it would take months of practice before I could type as fast on
the twiddler as I can without any practice on the 110 keyboard. In any
event what I do about serious typing is the same as Amanda Walker---I
plug a small Seijin keyboard into the kbd port on the back. On the
road I leave the keyboard in my room during the day and only use it at
night when answering email etc. while dialled up.
Incidentally the really nice thing about using compact flash is that it
frees up both pcmcia slots, so that you can get a serial port (needed
for the twiddler) using a pcmcia card (which adds nothing to the bulk)
instead of the port expander (which doubles the bulk preventing you
from carrying the 110 in your pocket). I use the Socket dual serial
card but so far haven't had occasion to use the second port, I got it
in case I ever used a modem or the Metricom Ricochet at the same time
as the Twiddler.