Shadow Priest might actually be quicker...let that sink in...The Shadow resist talents wnsure you don't get stuck with 10 million resists when you first get into a zone. Also, Spirit Tap is one of the greatest talents ever...with good timing, you can eliminate downtime completely. on my lvl 18 Shadow priest I bagged a 23 rare , and didn't have to find my corpse before looting it(Chatter)the combination of resist reduction, and massive mana regen means Shadow spec priest feels slow, but you will have a ridiculously consistant rate of kills, and you will have a much lower overhead. And at the end of the day you must face one important conclusion...there are entirely too many hunters in WoW...my Main recently left my old guild since, due to scheduling conflicts haven't been able to raid with them in 6 months, and there is a full blown Glut of Hunters out there. I am still suffering for the actions of the last generation of Huntards, right as the next generation is on the way up(little bit of bitterness).
Plus in terms of the future, with another shadow damage class on the horizon, there will be even more usefulness for shadow priests in the next expansion. The shadow priest-Warlock-Death Knight synergy will probably be the last step to bringing shadow spec fully into the mainstream.
And seriously, try a Priest up to 15, wand every mob down when they hit 30%-40% health with Shadow word:pain on them. you will not run out of mana unless there is an emergency. Less food, Less water and no bullets means less time in town.
PS- "of the Whale" is cheap, and actually useful!