Mistress,
Great question. Forgive me if I repeat myself in my response. My whole career in BDSM since the early 1970s (when I in college and answered a B&W Screw Magazine ad of legendary Belle de Jour because she looked busty and sexy) has been about pushing limits. I fell into this as a horny kid wanting to be with sexy older women. By the second or third session with Belle she had me as the sub in a training session and halfway into it anal play was involved. (She didn't ask, she just did it. Today? Limited play, butt plug, etc. but not the full experience.)

Years ago I never thought I'd worship toes or bare feet, but now I love it. Hand over-the-knee spanking? I never thought I'd like it, but now it is a sensual pleasure. Scissoring by a female body builder or a fit Mistress? What's not to love? LOL!

I've pushed limits on my own suggestion, such as outdoor play in the city usually at dawn on a weekend and I did that several times. But other times Mistresses who have known me well over the years were careful when in planning a session by phone or with me. The main activity where two Mistresses said, "Really?" is GS. Mistress Ayn, twice I had the same type of GS experience you describe, with me pleasuring myself. I never thought that would be enjoyable. I was in deep subspace both times I experienced it. You never know how your tastes change over the years.