With open cell foams it will change drastically. With closed cell foams, not much of a difference.

Must foams are closed cell nowadays, so it shouldn't really make that much of a difference.

I run with no holes at all, only inner side of the tyre glued to the rim, the outer side stays in by pressure.

Air kinda vents a lil' bit through there, I don't have any issues with the tyres coming out of the rims, and there's no dirt going inside.