LJ, I suppose the question is; what would you do if BI never implements the changes that you require.. and how long are you willing to wait before taking any sort of action in this regard? I don't think it necessarily is wise to completely depend upon BI to make the specific changes that you require (of course, I could be mistaken and ignorant to a prior announcement or whatever.. if that is the case, disregard this message). I understand the benefits of both releasing before it is complete and waiting till its completion, but I think the circumstance completely changes when the dependency of its release falls onto anyone but yourself. I think you should make decisions under the presumption that the engine implementations you require may never be carried out. Realistically, regardless if the mod is 99% done or 100% done, you are going to get pathetic, arm-chair warrior haters spitting their BS all over your profound work; the fact of the matter is, you've done absolutely amazing work that thousands of guys WILL appreciate regardless of its level of completeness.
I certainly fully support whatever decision you conclude with; just know, you have a massive community behind you on this and we are thrilled for all your hard work.