I kinda agree with WS here, as long as the reason you are not using your safe word is because you want to hold on.

I have occasionally noted that subs are unwilling to use safe words because they think that their Dom would be upset. I can assure you that this is almost always wrong, and that any Dom who does not like a sub to use a safe word should not be a Dom. In fact, if I find a sub is unwilling to use a safe word, I will step back from the intensity of what I am doing to avoid pushing that envelope so that we do not go to far.