Yes, plot holes do happen. However, because we obviously don't WANT any plot holes, it goes to reason that the most plausible theory is the one that DOESN'T involve any plot holes. The theory that is both logical, hinted to, explains a lot and avoids plot holes is the better theory. The theory that relies on 'coolness factor' is clearly worse.Logic was mentioned, and a always in the discussion, I make the case that in games like this 'can you logically assume it's true' is less important than in real life and 'does it make a cool story' is more important. After all, plot holes happen. So I agree that there is no definite proof that R=U, just some things I see as definite hints, but in the context of a video game, those hints are enough.
Saying that we should be looking for a 'cool theory' over a logical one is like saying Square don't think about the logic in their plot. As you said, Square do make the occassional plot hole, but on an overall basis, they spend a lot of time refining the plot.
And when it all boils down to the core arguments of R=U, they're simply not strong enough to make it a particularly plausible theory. I mean, it isn't even hinted to in the Ultimania Omega! In fact, the Ultimania says that sorceress have the same lifespans as normal people, which instantly disproves the theory anyway.
But anyway, all this can be found in my own and Squalls FAQ anyway, so if you want to continue the argument, you might as well read that through and argue against whatever's in there....