The M80s come into play for a variety of reasons:

1) They sound the same as the M60s, their advantage is that they have more headroom.

2) They are better than the M60s in a very large space. I don't remember the size, but it's bigger than most rooms we see.

3) They provide bragging rights.

Unless you have a realy big space or can't get enough ear bleeding, the M60s would fit most needs. Certainly doesn't hurt to move up to the M80s if that's what you'd like.