AEGs are the best bang for your money, and alot easier to work on, and parts are cheaper in the long run.
The WE G36 GBBR is also something I've drooled over quite a while...
So far the one I've seen in real life, has held up well to very harsh testing.
However, just the mags themselves are an expensive venture... almost 50 bucks a piece, and they only hold 30 rounds. To be "competitive" at any level against AEGs with mids, you'd need at least 10 mags for ammo capacity, and thats only going to give ya 300 rounds, at 500 bucks.
The guy I know who bought one, claimed it came with a airflow reducer in the box, that is supposto lower the FPS for CQB FPS, but I still do not think it lowers it enough for SOGO play... and, I can't honestly tell by any place that has them in stock, that part actually comes with the replica. ( I think his was a fluke).
So primarily, it'd be a field grade GBBR , fun to shoot... but unless everyone used a GBBR, you'd be at a severe disadvantage, both in ammo, and range capacity.
Also, keep in mind, the cold weather months, are not gas friendly at all...
Which is the other reason I'm holding back on the We G36 myself.