In thinking about the Between the Spaces storyline further, I'm considering new ways to use it - different game systems, maybe busting out a
VERGE game based on the story. In so considering, I'm thinking it could be useful to genericise the storyline - strip out that which makes it Planescape. Now, clearly, I'd keep those elements if I did something like run a BtS Planescape game (again). But I'm thinking the more ways I can use the story, the more versatile I am in telling that story. Especially if, as I mentioned, I intend to use it as some background to
Mission: Zodiac.
This is all sort of related to my issues with Ringwalker, as well. While I think he's an interesting character, and has a story of his own to be told, I'm not really sure how much it fits into Between the Spaces, other than a side story going on sometime during whatever happens in the middle. This is especially true if I want a non-Planescape BtS, as Ringwalker is intrinsically tied to D&D's Great Wheel.
On the other hand, I feel I can do a lot more (especially with Requiem) if I'm not bound by someone else's setting.
Really, rather than "generic" Between the Spaces, I think I really just want two distinct versions of the story - one set in Planescape, the other set in a world of my own devising.