For example, some people think they give kids an ego without providing much additional benefit.

I was in G/T programs as a kid, but I was kind of blind to what was going on so it is hard for me to really judge one way or another. I remember it being fun in elementary school, but I'm not sure that it challenged me in any meaningful ways. It maybe did later on, but it is hard for me to say whether it was better than just the Honors route (because I have no idea what that would have been like).

From what I've read, one of the most interesting pros is that G/T kids often do better socially in G/T programs. It is harder for G/T kids to relate to other kids because they don't think the same way, they have interests in totally different things, they can come across as being a bit weird, etc. So they are more likely to be bullied in regular classes. G/T helps them make friends with like-minded kids. I think that is probably a really important reason to put kids in there from an early age - get them a good group of friends before they get into middle school.