Picked up a Flexi-50 from a fellow TGP forumite and I must say, this thing sings. It will take a while to understand all the adjustment possibilities but my initial impression is in line with everything I read. I love how responsive and unforgiving it is. You can hear every nuance. The one thing I hate is the industrial metal case. It's nice that it can be removed with 4 thumb screws but I can't mount my guitar hangar to it and its ugly as a mud fence. Anyone rack mount this thing?