I personally am not a big fan of purism to a style just for the sake of it. I've never formally studied JKD, but do firmly believe in the concept of absorbing what is useful and discarding the rest. I try to study any and every form of FMA that I can. Right now, besides my studies in DBMA, I'm also spending some time on PTK (+also Tang Soo Do with my kids). But I keep an eye out for any seminars or training that I can find. If a move/technique just doesn't work for me (after really trying to apply it), why should I waste my time. Rather I should develop techniques that do complement what I can.
I basically agree with everything that Maija stated. Being the son of Filipino Immigrants to the US, I can say from experience that if FMA is like anything else in the culture, everything is politics and if you don't like something or someone, you just create your own group/style/school even if there isn't huge differences in style. Of course different schools may focus or apply things differently, but I would say that there is so much borrowing and adapting that there are very few pure styles of FMA.
By the way, I'm not a fighter, more of a practitioner and haven't been at it that long. And I'm a part time student of PeteJ.