But ultimately, I think, we train to enter the space and rotate our partner (not rotate around our partner). My ability to slip outside of the space would be the product of gaining the center space and choosing to move outside; the key difference being my partner's inability to track my movement.
Essentially, irrimi. Probably one of the hardest exercises I do incorrectly since starting training. Right up there with tenkan. Er.. irrimi tenkan.
To me that first sentence is the key one. I don't want to dance with my partner any more than I want to stand fast and dispute the space with him; I want to claim the center. Not that I am always successful....but I believe this is energetically and martially the purpose of opening move.