I do! My still says MBritt on the front so I guess it's super vintage extra special now, right?
Great cabinet. Took me a while to adjust to it. I was coming from a very dark-sounding EV ELX112P so the high end content I was hearing when I plugged into the XiTone was slicing my ears open at first. Once I solved for that and figured out the difference between the XiTone and my Tannoy monitors on my desk I've been dialing in sweet sounding presets without any issues.
The open back is the bees knees for me. You get that less-directive, room filling behaviour you'd expect when you take the back off. I love it. I don't think it'll float the boat of anyone doing the brootalz. The low end won't hold up as nicely as it might with say a ported, closed back cabinet. But for the kind of rock and blues I play it's just great.
I feed it a sub-mix from my Behringer mixer that's mainly my guitar signal and a little vocal and band and it's my "wedge" for monitoring like that. If we're playing without our personal PA support I just feed it my III's signal and run it like I would an amp behind me on stage.
Also: Mick's support is Fractal-like -- which is to say it's amazing.