I've tried really hard to make it "feel" as nice as possible -- it's even got a nice weight to it... lol. The only ROM's I've had issues with as well have had dodgy headers (mostly no headers at all), so experience with home brew will be a bit hit and miss until headers are sorted out.
However the actual code to deal with file formats is part of the menu code on the Lynx -- it just instructs the cartridge to write certain parts of the file to certain bits of the cartridge memory, so there's scope to create new formats or do some more intelligent guess work at what the format should be if headers are missing.
Edit: GadgetUK's Video added to the fist post as well as it's a great overview of the cart, and I don't think I've actually posted proper final cased shots. So this shows everything really nicely!
Lynx Multi Card Preorders
in Atari Lynx
Posted
Just saw it, add me to the list as well good sir.