Hmmm...I'm very tempted to give the Viking 512M card a try. The specs look the same as the Viking 256M card, which seems to work fine, so it just might do the trick.
And...There's a rebate on right now, so final price on Amazon.com is $155. I hate spending so much on memory, but I got a great price on the MR-8 (Musician's Friend scratch and dent special) that would help make up for it. Amazon's return policy is pretty liberal -- I didn't see any special exclusions or restocking charges for memory cards.
I just might have to take one for the team...