Perhaps blizzard already thought about the difficulty lvl each class will have with the cap flag expereince. Who knows maybe theres more then just that way to gain experience.
Some crazy ideas.
1) Heal the FC. FC caps flag. You get experience too.(Of course this applys to healers.)
2) Help deal %damage to the FC. You dont return the flag but someone else does. You still gain some exp.
Imo the biggest shame of this is Blizzard has their hands cuffed in how good they can make BG leveling and rolling on loot being directly competitive to PvE leveling and raiding for loot.
One is extremely boring/redundant vs another being a lot more enjoyable in the moment, and its too bad that leveling and getting loot through BG's will be tied down as a result of the tedious/repetitive that is PvE in WoW.
It just seems wrong that player enjoyment isn't the primary focus, but a necessary evil or it completely trivializes the whole lvling, 5 mans, and raiding that PvE was built upon, if the PvP equivalents even came close.