Rizzo, here is a
link to a thread of a comparison another forum member and I did last year on the differences we heard between the M22, M60, M80, it may help in your decision on what to get for mains. I will also say that the findings we had on the M22 are not the norm as I have no thinness issue with them in my own home and they sound great. The M60s I found to be a very nice speaker once I stopped comparing them directly to the M22s and ran them on their own after we did this comparison. Personally I think that anyone of the 3 would be a great speaker for your room size.
The EP500 sub or even the EP600 would be the way to go for your room, as was stated you can never have too much sub. It all depends on how much you are willing to spend.
