On Topic: If anything, the new talent trees give Blizzard even MORE reason to only give us 3 stable slots:
1 DPS
1 Utility
1 Tank
As for the pets leveling in raids... It really depends on what your guild is doing, and whether or not your guild has that content on farm. I brought a level 69 Owl into Hyjal because it had about half a level left to go, and it was level 70 before the first boss. Each mob didn't give a lot of experience, but there were just so many of them, that my pet leveled fairly quickly.
I would never take an under-leveled pet to anything BUT Hyjal, though. 25-man raid trash doesn't give much experience at all. IMO, the best way to level a pet is to find some nice farm spot and start killing things. I usually find places that drop Aldor or Scryers rep.