I'm very happy. I've been running my bass into a PA with either an fDeck on Radial BassBone and haven't liked what I hear. I got my GK MB200 a few days ago, and got to try it out through my Avatar B115 at a couple gigs this weekend. First with a folk band with banjo and electric guitar, and last night with an alt rock band that had a nylon string acoustic and drummer. Last nights gig was by far the loudest of the two in a venue that holds about 100 people. PA was for vocals and guitar only. The amp held up great, and the volume never went past noon. I could hear myself fine, and the EQ did great to give me even string balance without the use of a preamp. Rig was Cremona upright with Sixrounds Original pickup straight into the MB200 and an Avatar B115. Cheap rigs can sound good too, and I'm really happy with mine!
I'm still happy with my MB200. For what it's worth, I determined the "flat" settings for the EQ knobs: http://www.talkbass.com/threads/gk-mb200-flat-settings.769404/ Of course "flat" is not the holy grail, but it's been my experience that it can be useful to know what the amp is doing, when dealing with issues such as room acoustics.
Yes! I remember seeing that a while back. I've been meaning to reference it again just to see where the EQ stands with my bass. I had it set pretty close to that at the last two gigs. Just the bass set a bit lower to cut some of the boominess.