There's one emu I recently ran into (since I was in the same situation). It's snes9xTYL 0.4.2mecm. From what I've tested some games run a little bit faster and the multiplayer does work. I tried Mario 3 from super mario all-stars (the battle mode) and it worked very well. It did have some lag but I haven't done any tweaking as it was a test. My psp was 4.01m33-2 and my friend's was 3.80m33-5. Hope this helps
O forgot to mention that during that particular game you can "control" the other persons screen. When you scroll thru the mario games on your psp, it's happening on the other psp as well. vice versa too. The image is also on both psps not one.