Well if you're going to call the JAC's that, all guns made before, say, '94 would have to be "unreliable gas hogs."
No more of a gas hog than a paintball gun, really. No less reliable than your average GBB pistol. (Which, to be honest, isn't that reliable.) It's less of a question of reliability (or at least, wasn't) because you could hop to your local store and buy some replacement parts (obviously speaking of Japan here.)
So to end my long-winded post (which I don't think actually made any real point) they were reliable enough.
The advantage is, though, that the build quality was MUCH higher. Some JAC's had milled barrels. You could run your finger along the barrel and feel the grooves from when it was machined. The Youth Engineering MP5 is made from STAMPED STEEL. Not pot metal, but STEEL. Think of the quality of a Sun Project M40, and compare that to your Marui AEG. No contest.
