The only difference between A and B is for A all the free levels will only be available to your main acct. For B you will have free levels for 1,2,3, and 4.

I just recently got 4 new accts and referred them all with my main. That way I will have 120 free levels to use on my main acct chars. Eventually I may decide to stop multiboxing, and after I am done I will have multiple 60s to mess with. That's what I would do if I were you.