This is an interesting topic and here is my perspective. I think pegging can be both pleasurable for the sub as well as powerful for the Domme. For me it just feels good after a good long tease and denial and that is where the power transfer occurs in my mind as I am tied down or in a position where I have no control and no choice. Add to that toys like a Tomo or Hush prostate milker and it becomes even more powerful. My Mistress has done that to bring me right to the edge multiple times using those devices and T&D and then locks me in chastity when She begins the pegging and does it for as long as She wishes to. It ends when She feels I have been completely milked dry and She has rammed me enough to satisfy Her with my total submission. At that point She relaxes for tea and a foot massage leaving me totally frustrated and locked in chastity. That is true power knowing the last time I was allowed a pleasurable O was 17 months ago.