Russell put it that the rational view is agnostic - even if the practical impact is negligible. You can find good TMA schools and decide if there's anything worth learning. Or you can wait for someone to come to your club. Either way is ok. Neither way is an exhaustive search. The problem is people in their ponds claiming they've got the whole ocean wrapped up. Even MMA is a pond. Most of us live happily in our ponds. That's ok too.
I am my own source. I don't think any better can be reasonably claimed from the current state of knowledge. Claims about 'effectiveness' of techniques / training methods / systems are statistical and there is nothing *remotely* close to passing for a valid statistical study. Starting with a consistent, measurable definition of 'effective'. Instead there is illogic, rhetoric and hubris under the banner of science. This is bad for communication, bad for martial arts, regardless of whose art is more effective blah blah blah.
I've trained Sanda for 'many' years. Some individuals who've trained forms for 'many' years have rolled me over with consummate ease in gloves off nhb sparring, some of those same have done similar in self defence. They've got no interest in entering an MMA competition and nothing to prove by doing so. Put gloves on them and spar Sanda rules with me and their dominance vanishes. That's my experience. I know that the 'traditional' arts we train can be applied effectively and that I can apply them effectively against some individuals. I also know that context matters. I don't know if I could apply other arts *more* effectively given the same amount and quality of training. My plate is full at the moment with enough to learn - good enough for me. But then I'm not claiming my art / training methods to be more effective than others.