I'm using my M4 with a mesa boogie 20/20 and it sounds great.Although I guarantee my vht 2502 would sound a lot better I just don't want to deal with the weight issue.
I use my M4 with a 20/20. If I could have louder stage volume, and weight and space wasn't an issue, I'd probably try a 2:90, but given my needs it works great.