I have had the MG-1 for more than two years now and am very happy. It comfortably replaced an Origin Live Silver and I think the improvements the MG-1 brought were comprehensive across the board. It might be a giant-killer arm at it's price.
A few issues I should mention - the quality of the arm wand itself is a bit iffy. It's plastic, and it actually cracked a little because of my over-tightening of screws. I got an additional, premium lighter arm for the setup (also bought through ada on the site - it was about $200) and I ran into similar issues, but overall, crack and all, the arm still sounds wonderful. If you're careful this shouldn't happen. The air-bearing tube (with holes) also appears to be plastic, but that hasn't caused me any issues.
The rest of the assembly is metal, very sturdy and seems well designed.
One other potential issue is that I haven't found a good way to ground the arm which can cause static build up sometimes. Finally, you have to be very careful in applying the stylus to the record - there is no soft landing, so you need to swing the lever slowly. I recommend praacticing a lot with a cheaper cartridge first.
All told, it's an excellent way to try an air-bearing setup. I find I'm not tempted by any of the $4k arms out there like Triplanar or Graham Phantom - maybe they would be better, but I'm really not so sure, as this arm sounds so good. Apparently the arm is modeled after the AirTangent, and if you compare them they do look very similar and operate in the same way.
You definitely need to arm yourself with the right tonearm protractor/measurement tools to get the setup right, but overall I've found the arm pretty easy to set up. You can see a photo of it setup with my Teres 255 on my virtual system.