I have the M60's and they are a great speaker for what you are looking for. Not too in your face but there when you want some punch. I moved out of some paradigms 9se and could not be happier. Make sure you match your center though as it will give you the overall sound you want. I have not heard the M80's but have heard that if you have a smaller or even mid sized room that the 80's may be a little too much. I would go with the 60's. Have not heard the M50's but if you are upgrading the room size why not go a little bigger just in case...I think that saying should be every HT guys motto.
