There is a great book, available in part through books.google even, called At the Side of Torture Survivors, which makes the argument that torture's only goal is the destruction (or sublimation) of the individual identity, to allow the torturer/dom to imprint a new identity.

I'm quite interested in the description of how this 'new identity' is created; the tormentor obviously can't supply all of the details necessary to form a cogent identity, and in fact one supplies very little, just a kernel. The remainder is supplied by the victim/sub who has to subconsciously guess at what to add; part of the function of terror in torture then, is to make sure that the subby crafts a new identity that you'll like.

Based upon descriptions of sub-space and descriptions of what its like to have your identity disintegrated through torture, I think the two are pretty similar... though I've never been in either position. I can't help but wonder if sub-space is just another way of describing the abrogation of the individual.