@Cheri Must it be either/or decision? How about this: 1. finish your Ellie Tappet and Kat V. books already in progress, 2. keep taking notes and world building on the space opera as things come to you, 3. after the current Kat V. novel is out, focus on Ellie Tappet as long as ideas keep coming and the Muse is with you. That way you can pay the bills. Even a couple of years of Ellie Tappet alone is no bad thing. Eventually you'll need a break from Ellie. I'm thinking that the space opera will be that much richer when it finally breaks out of it's vat and you just have to write it, NOW. And same way with Kat V., eventually you'll get back to her when it feels right to you. Or something like that. In any event, what works for you is the right answer.
I kinda say all that for a selfish reason: as a fan, I don't want Kat V. "finished off" just yet. And I'm willing to wait for that story to continue on in it's own time. :-)