I'm cool with either GPL or CC allowing alteration and redistribution; I tend to change things and re-optimize assets I use, and I hate having to put little "you can't use ABC, because I'm not quite sure it's legal for me to give you permission to re-use it" clauses into my mission statement / license
I think more people will use it for things if it's CC-SA-NC (i.e., you get credited explicitly, non-commercial use only), because people get very freaked out by the GPL's clauses concerning the rest of the "work" and applicability to same. I know enough about the GPL that I don't care; a piece of GPL content is "mere data" and would not put the code of a mod or game under the GPL per se. But I think a lot more people are comfortable with CC licenses, because of that perception. Just my two cents; I've dealt with lots of license whining elsewhere because of GPL'd stuff I made.
Anyhow, just thought I'd bring that up; people have been complaining since I released Blood and Steel about how I didn't use Polished Landscapes' flora, but the license issues were at the root of it; I didn't want to use it and offend you by granting others permission to re-use, or even worse have to pull it and look like a jerk. I made the decision to be Open Source pretty much immediately; I hated the idea of using and improving all the OSP stuff I used and then saying, "you can't use this"
If you ever do any more work with flora, I might be willing to help out; I reworked most of the Taleworlds flora for the mod, it's not a biggie for most things. If nothing else, it'd be pretty nice to lay out 2-3 more sheets for random bushes and flowers and make the flats.