I'm surprised no one mentioned the
DSI Modular Mac yet...or, actually, I shouldn't be because only two people here seem to own this board, and SirClickAlot's the other one.
No PS/2 support for full N-key rollover AFAIK, but I tried it with a green PS/2 adapter, not a purple one (as if they might be wired any differently). It probably wouldn't support it at all given how the target market would've used ADB instead of PS/2. Still, I haven't found anything that disproves 6KRO over USB.
There's also some big rubber feet on the bottom that provide a good grip. Mine hasn't slipped on me yet!
The only detractors might be the non-standard layout (it's not simply IBM extended with the numpad cut off, as the pics show) and users insisting on Win/Cmd/Super/Meta being between Ctrl and Alt, as well as it now being $100 instead of $80 like it was earlier.
But if you're going to hold off for the Leopold FC200R, that's fine too. Looks like quite a nice board, actually, and I like the detachable cable-a feature I might miss if I quit using my Model Ms.