They aren't available in the US, so that will limit the responses you get from AVS members. When I contacted MJ asking if they had any plans for US distribution, and/or wanted to submit a unit for evaluation, I was shocked to encounter a very nasty and unhelpful person, so I can't tell you if anyone in the US will ever be able to get one to try it.
From what I can tell their specifications are borderline fabrications though. The PRO 50 MkII, for example, is a 10" acoustic suspension subwoofer with a 120 watt amp that supposedly goes down to 13Hz. Riiiiight - I'm sure that's accurate.
Bottom line is you'll probably get a better response by asking on UK forums. I'm not sure if they'll ever be available in the US, and based upon my exposure to them I hope not. We don't need a manufacturer with such a poor attitude.