I doubt very much there is any significant differences, or they would have remaned it, like they just did with the T2 "upgrade".
Unless someone has actually been involved in it's design or programming I would not put too much into what you hear, as there are always the ones who want to feel superior, that their new detector is the best, or that they know something you don't.
I did see a post the fellow mentions how quiet his version 6 was running, Im sure it has a lot to do with the ground and SENS level. Where I live there is a lot of iron, and hot rocks almost every where, I run mine at 99 SENS almost all the time, it's version 5 yes it makes some noise, but so does EVERY other detector capable of similar performance. IE a coin to 10+ inches.
There's a new update of the G2 coming out very shortly they're calling it G2+. So again if the Omega had any real improvements in version they most likely would have renamed it too.