with the Nimbus Old Monkeyshine mod.

The button layout works well for both SNES and Genesis/Saturn layouts, and with d-pad, analog and all the buttons, you can hack together a workable N64 layout. For PS1 you're missing the dual shoulder buttons, and a separate (or, alternatively, properly placed) start/select buttons. Its replacement, the P990, does have the dual shoulder buttons. It doesn't bother me, since I don't do any PS1 emulation.

I'm reasonably happy with my P880, although the mod made the buttons stick, and after pulling it apart to clean it, the shoulder buttons are a little flaky unless you push hard.