I like the MC2255 in my living room quite a bit. I haven't compared it with the amplifiers listed in this admittedly old thread, but I would prefer to upgrade my Avalon NP2s before upgrading the amp.
But, to address the amp in question, on Saturday night I was loaned an MC2300 to power my bass rig at the Aggie Theater in Fort Collins in Colorado. I've played through all kinds of high power amps (my regular amp is a Quilter that is rated at 800 watts into 4 ohms and I've also used the large Crest amps rated at 500wpc into 8 ohms) and this sounded really, really good. I doubt I'd bring it into my living room and I definitely need roadies to schlep it, but it would be my amp of choice. And yes, we are a Grateful Dead band, so with a '67 Starfire with Alembic guts and Alembic preamps, it does a certain thing with perfection.