I was asking about these myself on here a little while back. Nobody seems to know anything about them (perhaps they're new to the market). The specs are a bit confusing, but it seems the amps only go down to 50, which is surprising for a small inverter. I'm not sure how useful they would be on thin steel. You can get them for a lot less than the price you mention though (link), which makes them in the same price range as the R-Tech 180!
If your after something a little more up market I'd suggest the Kemppi evo 170 or Esab caddy mig 200 or Gys pearl 180. All 3 can be picked up between £750-£850 and are in a different league to the Rtech, par welds with there senergic lines and plate thickness settings, Q set etc. if money really is no object then the EWM pico mig 180 is without question in a league of its own but costs around £1500-£1800.
Did you get on alright with the Parweld Gerry (I seem to have it in mind that you hired one)? I'm still very tempted to get one myself seeing as they're pretty well spec'd for the money ...variable burn back and inductance (although I'm not sure if that's all that useful on a small output mig), wire speed display and inch-feed button. I just wish there was some info out there about them!