IMO, if you really like an exotic pet then you should just stay BM. Reading an article on the internet that suggests one spec for leveling doesn't mean you have to go that route. Of all classes in the game, hunters suffer a lot less than others in the 'inefficient spec' department. I would imagine you could stand back and auto-shot mobs and be fine for the most part. Play the game how *you* want to play it!

I'd stick with BM if you wanna keep your corehound, that's what Im going to do! Hunters have gotten a really good roll this time around, and I think all three specs are quite viable and good for leveling. Frost is just suggesting the most ultra super fast method, but I don't think the other two specs are going to be that much slower. I personally haven't liked the feel of MM, so Im sticking with my BM and SV secondary. Its good to consider other options though, and if you're not dedicated to your secondary spec, hey, why not give this MM build a go. :)

I recently leveled my hunter to 80 (I was level 64 or so when 4.0 launched) and I still found Tenacity pets to have better threat than Ferocity since they have talents to boost it. Once they get a Thunderclap off you'll be hard pressed to pull aggro before the mob is dead unless you're doing something silly like Distracting shot.

You should still be fine leveling with your Corehound, just keep a Tenacity pet on hand in case he starts taking more damage than he's ready to handle. I would recommend a Turtle/Beetle for Shell Shield.

The nice thing is how cheap Dual spec now is! So I get to keep Loque'nahak to trot her around when in Daralan to impress the neighbors AND zip around with faster flying speed for mining and motes. But when I need to knock heads, I change to MM and my White Ghost Cat from way back when.