For the heartache, I would say buy an A3000 or A4000 (or even A2000 if you can live with it's 16-bitness) and go with a busboard and call it a day. I mean there's so many greeblies you can hang off of an A1200 board in a tower but then you've got issues of "Well is it compatible with my motherboard, okay now is it compatible with my motherboard and my accelerator, now is it compatible with my motherboard, my accelerator AND this busboard, AND this version of OS3 and and and..."
If you want a souped-up A1200, I would:
Keep it in the desktop case
Wait for the Vampire A1200
Then add a USB solution for external connectivity such as memory sticks, mice, 16 bit sound.
