I've heard bad things about star internals and their plastic, from what little experience I have their metal seems ok but that's by no means a weighted opinion lol
What did it for me was the functional bolt catch on the G&G, despite G&G having what seems like the crappiest metal of the mainstream manufacturers, luckily the UMG is plastic
I've got nothing to tell you about the STAR's performance, but my own G&G was shooting anywhere from 160-220 when I got it, incredibly accurate though somehow, I put about 80$ worth of parts in and if I had stayed in flecktarn BDUs I'd be using it as my outdoor gun!
Other people with UMG's don't seem to have the same ridiculous fps problem I had, but it could very well have been caused by improper lubrication from factory.
The mags are a mystery, I have 70 round mags, they hold 70 rounds, the bag they came in stated they held 70 rounds, yet on both redwolf and WGC they say 50, and all the mags Mark brought in after mine said 50 on the bag...
Not to mention the mag springs are so damn strong you can hurt yourself unloading them! We tested the spread on a mag, 70 rounds travel about 20 feet with a 4 foot spread, try duplicating those results with any other mag lol