I think I was wrong about there not being a limit or at least having not reached a limit. by the looks of things, I think only 3 units can be tied together with the same account. if you add a fourth unit, it's musical chairs behind which one will be deactivated. I need to call Nintendo tomorrow to be sure of this. if this is the case, I'm going to sell my hackable unit on here, possibly with a 1TB micro sd card included (and screen protector applied as well as dock, no cables).