I went to the opening of Pandora - The World of Avatar and had lunch with Joe Rohde, the Imagineer in charge of Guardians. I asked him about changing TOT and his response was interesting. He said he never, ever, felt that TOT was a classic at DCA because it hadn't been around long enough. The show was not great, very slow moving at the start and that the butt air-time lacked. He was super stoked (as he should be) on Guardians and the story line. He was especially stoked on the amount of butt air-time you get now. Funny enough, Guardians seems longer but it's the exact same ride time. You're just doing more up and down than sitting and watching.
However you feel about it, there's always a TOT in Florida and it's not going anywhere for a long time...and my personal opinion is that the one in WDW is much better anyway.