My only gripe with the amp (and I have the combo) is the weight. The amp is very large and awkward to carry, especially up and down stairs. This has not caused me to sell it, although the thought has crossed my mind. I find it easy to get a good tone at reasonable volumes. The amp was designed with this in mind.
I will add that it does take a little time to dial in, depending on the tone you are going for. For instance, I have been trying to find a decent Rock & Roll tone, e.g. Chuck Berry and Brian Setzer. It took some time, but I found it on the clean channel with the master cranked and the gain at about 1:00. The bass was turned down below 9:00 and the treble was at 2:00. I know that as a general rule, Mesa amps take a lot of tweaking to find your sound. However, I thought the RA100 was an exceptions to this rule. I wouldn't call this a gripe, but knowing this might have saved me from some initial buyer's remorse. Overall, I am happy with the amp now that I figured out how to get the tones I want.