well, the biggest card the axim and most pdas can accept is 4gb, which is about 2 hrs at 24/96 (as two seamless 1-hr files). I have yet to cross two hours at any show, and if i feel a band will play an uninterrrupted 2 hr+ set i'll roll at 2448 and get 4 hours.
gordon is currently rewriting the flac coding for live2496, the previous flac code didnt work so hot for 24-bit. flac works fine in 16 bit and will let you get like 14 hrs of 16/44 on a 4gb card
once the new flac code is out, 4 hrs of flac'd 24/96 on a 4gb card is in order.
also there are some peeps working on a hack to enable sdhc cards on the axim, which would allow for 8gb cards.
either way, its viable now, and soon to get better once the 2hr per card limit at 2496 is broken
in any case, aside from storage limitations, the pdaudiocf is the most relaible interface ive used since the vx pocket. live 2496 has never failed me when the pda is set up correctly (I've tested 100's of hours at home and am probably coming up on 100 hrs of field use)
your 2210 is a pretty old model, prob. doesnt have the cpu to keep up with 24-bit. the axim x50v runs at 624 mhz, and i get 6+ hours of recording off a charge at 24/96, with very low buffer/cpu usage. those axims are only like $225 on ebay, and have a nice vga screen. I bought a 16gb CF card, and am using it as my primary dap/video player as well.
have you confirmed that this pda will record @ 24/96 for extended periods of time (say 3 hours)..? my pda (h2210) will NOT, though it is terrific @ 16/48.
i was thinking of ditching the pda setup for hi-rez work, and going up to the new fostex machine...