As one of the few teenagers of SL that doesn't want a Grid Merge, I personally think that LL should just move the land that is the TG now to MG and make it so that teen-access only - a safe-haven for teens - giving ratings of TG, PG, M and A. I also feel that LL should make some kind of indicator on teen-tags to show that they are teenagers, like if on a TPV, you see the viewer written in brackets beside the user's name. Just have that, but with "Teen" or "TG" written it (E.G. Midnight Firecaster (TG) (Phoenix Viewer)). Solves all the hassles of whether people know whether or not we're teenagers then, right?
Also, at some of the people who have said about teens being able to alt-cam into Mature Sims and see Mature and Adult contents, teens have been on the MG for years hiding behind false accounts. It's going to be no different from how it has always been, only this time, you know for definate that we're on the Grid.
I agree with what most of the people have said on this post about how the teens are immature (You should see the TG sandboxes), but you have to think to yourselves, not all of us are mindless, spamming fools. Some of us can actually bring something good to Main Grid.