I'm using Kombi tips, I found isolation to be significantly better than any of the other supplied tips. Very comfortable, bass hits deeper and harder due to the improved isolation. They also truly bring out the details of the music.
I think they go very nicely with the PM4 as well. The only downside is the difficulty getting them on initially. They give a great mixture of isolation and convenience, but it always takes me a good few minutes to wrestle them on to any IEM I try them with, even the Trinity ones!