I think it largely depends on your views on the importance of the base to the quality of the final curries SL. If, like me (and several others here), you believe that "BIR magic" happens in the base, then you will, for sure, do well to explore making your own. Least of all, you'll develop a good (or better) understanding of what a BIR base is (or should be) and how it influences the quality of the final curry (with regard to that allusive BIR taste, texture and smell).
However, if (like many others here, possibly including you?), you believe that the "BIR magic" almost entirely happens in the final curry preparation (i.e. due to "technique", or whatever) then you would probably do better (unless you think you can develop a better "BIR-like" base than exisitng ones, of course?) by picking a "good base" and concentrating your efforts on final curry preparation (which is the view, I think, that you have previously expressed?).
To my mind its a combination of both. But, for me, the "missing bit" (or "secret", if you like) is mainly in the base. I'm referring to BIR curries from yesteryear, of course.
PS: Don't you just love the way in which a few ciders provide inspiration!?
