The G80 is good if you know how it works. My old chevy had one, and I could feel it when pushing back a snow pile. As one wheel started to spin, I could feel the other bite and get just a little more push out of it.
But since the G80 works on a difference in wheel speeds to engage, one tire has to spin a little before the other kicks in. Once it is engaged, it will take everything you can give it. But the issues with those is people not understanding that. ANd being stuck, just dropping from drive to reverse and nailing the gas trying to rock. Well when you just nail the gas, The one wheel starts spinning very fast, and then when the G80 engages the other side, it is rough on it. And it can turn into the "gov-bomb" as everyone calls it.
Oh, and the G80, you cant tell if you have it by jacking up the rear and spinning one tire and seeing which way the other goes. Cause it will act like an open diff. You have to look for the RPO code, or there is an other way, but more dangerous...With the rears in the air, and in 2wd, have someone put it in gear and try to maintain a slow speed, like 5 mph. With your hands and heavy gloves, try to stop one of the tires. IF an open diff, you CAN, and the other will be running twice as fast. If it has a G80, you can start slow the one tire and the other speeds up, but then it will engage and you cant stop the tire.