Thx a lot guys, that makes my decision much easier. I'm impressed that so many prefer using a single bnet.
I'm pretty sure now i will stay with my Main Bnet Account. And once i be able to buy Tokens again, i will spend 24 Tokens in the Master so that this account is always free to play.

I also feel that I never wan't to make it a job
thats pretty much it what it feels like for me, and that feels badman.