do you think that the sub is really the person in control of a dom/sub relationship?
I'll answer too, just because it's an interesting question to me!
It depends on the degree of the D/s relationship. I have a lot of friends who kind of play around with BDSM as a bedroom game. In that case, yeah, definitely, the sub has control in the end, with the safe word and discussions of what the night's play will and won't involve and what have you. I have another friend who lives it as a 24/7 lifestyle. She absolutely does not have control, does not want it, and resents when people think she does. She did in the beginning, of course. It was absolutely her choice to be collared and give herself over to her Master. But now? No.
I think both are perfectly valid choices. It's just too broad of a field to generalize.