The ejection port is considerably smaller on the Airsoft version, and the body tube seems to be a bit smaller in circumference as well, at least as compared to my Hyperfirm ROTJ E-11, though that one IS cast off an MGC model Gun as opposed to a genuine Sterling. Other than that, the dimensions are pretty close. Here's me using it at a troop:
http://www.goldengategarrison.com/gallery2..._17731.jpg.html
The little tube you see sticking out of the back is a quick-release fitting in the gas tube, which is something you'll have to live with unless you want to really get into the guts and do some tinkering by adding a push-to-fit fitting or something like that. Though admittedly I don't know if that's possible, as I haven't taken mine down that far yet. You might be able to cut it shorter than I did, but I didn't want to screw it up so I left it a little longer. You also need to custom build a magazine unless, like me, you cut down one of your magazines. Cutting it down to the more or less proper length will cause the mag to no longer be usuable for shooting due to the internal construction of the mag. The inside of the magwell is contoured to fit the airsoft magazines, so a real mag will not work without considerable modification, if at all.
Also, I think the rear sight is somewhat smaller than a real one. The rear half of the body is plastic, and the front section, with the vents, is metal. The muzzle looks good, but as the body is slightly narrower, it strikes me as being on the small side, though as I mentioned, not very far off at all from the Hyperfirm I have.
The metal stock is nice, sturdy, locks in place... More just a neat feature to have than practical. After all, when was the last time you saw someone actually using the stock? The whole thing requires a repaint, as the stock, plastic rear portion, and metal front portion all have contrasting colors/finishes. Once everything matches though, it makes for a very nice, if somewhat hefty (compared to most trooping blasters I've seen) piece.
Other additions to mine: genuine scope, saberfreak T-track, homemade scope rail, Hyperfirm Hengstler.
Overall, I'd have to say if you've got one, or can get one, I wouldn't be afraid to troop with it. It's quite sturdy. Much more so than any resin ones I've seen, provided all your attachments (scope, track, counter, etc.) are secure! Only thing is, like the MR, it WILL be fairly hefty once you've got all your bits on it, so if holstered, it WILL drag on your belt, depending on how you have the belt attached, and be prepared for stiff arms after a long troop!