What seems interesting is if you do the Heroic quests and the Bonus quest series you outlevel the area. If you do the solo bonus quests or the heroic quests but not both you will be spot on. The bonus quests seem to be there for soloers that skip the group stuff. Just an observation.

Really if you are racing to max level to grind content then you are missing out on the main point of the game. Leveling in SWTOR is easily the meat of the game and is meant to be enjoyed. Why anyone would want to skip the stories just to hit 50 and be bored is beyond me for this game.