Ok. like I said in the title this is only a theory but if what I am thinking makes sense it should allow you to lvl up two characters super fast. Well, its two theories.
Mind you I have not tried any of this, in fact i don't really understand how the recruit a friend thing works anyways I just wanted to tell you all my theory. Mind you this is going to cost a good chunk of money.
THEORY 1
For my first theory, I am thinking that you can level up to two characters to 60 at the same time. This theory has two parts to it cuz i don't know which accounts gets to give the levels away.
A) This is if the Friend Account gives away the levels. Also, this depends on if you can link a friend account with your last name. Ok, so you make the Friend Account and upgrade to BC. Now, you make this character that you can easily level up. So, I suggest using a guide or something or one of those easy classes like rogues. So, you level up to 60.
THen you log on to your main account and create say a paladin or something harder to level up that you also want. Level this guy to 30. (This should take only about 4 or 5 days.) Then on your Friend Account level this guy up 30 times. Now you have two lvl 60's. Transfer the class on the friend account to your account and you have 2 lvl 60's on one account in a matter of maybe a month or so. Depending on how fast you are. This will cost you about $60. But it is worth it.
B) This is if the main account gives away the levels. Ok, so you make the Friend Account and upgrade to BC. Now, you make this character that you can easily level up. So, I suggest using a guide or something or one of those easy classes like rogues. So, you level up to 60.
Create another character on friend account and lvl it up to 30. Then on your main account give the 30 levels to the lvl 30 character and you have 2 lvl 60's. Then just keep the Friend account as your account.
THEORY 2
This one requires a level 70 to get full effect.
So, on your main account (The lvl 70). Do ALL 25 Daily Quests for the day but do not turn them in. Summon the level 1 character to you and turn in the quests. Rinse and Repeat. Since the lvl 1 gets about 30k. (I think with x3 quest xp bonus + The normal 10k xp for the quest.) He will get up there pretty fast. Now I figure you will ahve to do this for maybe or 2. And the link lasts for 90 days. Cuz I mean even at the early 60's you will still get 1 lvl a day. And that's just from doing dailies. In your 50's you will get around 7 lvls a day. Since the link lasts for 90 days. You can get probably around 7 or so 60's. And you can level your 70 to 60 too if you wanted to switch accounts. Only problem is u will lose all your gear. But with expansion coming out soon it won't matter much cuz all your gear will get replaced by quest gear.
This is the cheapest way only about 30 bucks. But you will lose a 70. Or you could level up your friends character really fast making you lose $0.00
As I said before, these are just theories. So, if you find that one of them won't work tell me please.