I went from M22s to M60s and was glad I did. In my room (11.5' x 18' x 8'), it made a slight, but very satisfying, improvement in fullness. I cannot say, for a certainty, that it would do the same for you, but I'd be surprised if it didn't.
If multichannel music is indeed important to you, adding the M60s, and moving the 22s to surround duty is an excellent idea. I think the improvement over your Dynaco's would be startling.
If you ever find yourself getting deeper into HT, you could go to 7.1 by adding a pair of QS speakers for surrounds, and shifting your 22s to rear surround duty for HT, while still using them as surrounds in 5.1 multichannel music.
I don't think the 60s would be overkill, and the 60s will blend with your VP100 just fine.
