I used to run a 2nd gen Max FLo on my Retro Valved Minimag a few years ago. Got rid of it cause it was just to big n' bulky, and didn't have a bleed valve on the reg. You could shut it off but you couldn't bleed the valve like something like a CP on/off will do. I ruined a quick disconnect when I 'popped' it off without thinking with air still in my line and valve.
I didn't RT that much anyways so I switched to pre-set tanks and on/offs. Plus with the new Ninja SHP regs, the old adjustables are a little unnecessary to me. I'd rather just have a seperate screw in Ninja SHP tank meant only for RT purposes that I could use easily on any of my mags.