Heres my take based on advice I have received from others on this site when I was trying to decide.
The reason I asked what music you listen to is that music is not all recorded optimum levels of quality. A most of the newer stuff and lots of the old stuff can be compressed and/or clipped because of the volumes they are mastered at.
If you had answered that you listen to a lot of classical and/or jazz it would be a no-brainer. Much of this material is well recorded and plays well on the M80s
The stuff you listen to may fall into the compressed category and may not benefit from the detail that the M80 is capable of. Some of it may actually sound worse.
So, my guess would be that you would be very happy with the M60s as fronts as they are more forgiving of less than optimally recorded material.
Your comment about bass and the music you listen to suggests to me that you would like the harder hitting PB13 more than something like the EP500.
If you are within 3 hours of the nearest city with decent audio dealers you owe it to yourself to go and listen to some speakers before making the decision to buy. In the end, only you know what sound you like so others advice is at best a rough guide.
Also, look in the Hearing Things forum and post to see if there is someone close that can give you an audition. Nothing can replace listening to the speakers you want with the material you most like.
Hope this helps. I will now let those more experienced comment/correct where appropriate.
