If you're sure that you'll stick with stereo listening and you don't listen to pipe organs, I'd get the M80s, you'll need nothing else. I've started to build my system slowly over a year ago and still didn't buy a sub. The only thing I am missing is the rumble from the LFE in movies, although if I play the movie at high volume I still feel my floor rumbling, they're able to produce that much bass. I had the chance to A/B the 60s vs 80s at the Axiom facility. At high volume, they both sound extremely close but at lower to moderate volume, the M80s have the edge IMO. To me, that + the extra bass extension + the bit more detail in the mids was worth the extra $$$.
"The problem is choice..."