I've tried the Tantra thing 3X in my early hobby days and the sessions did not leave a strong impression on me to the point that I don't even consider Tantra as an option. Hindsight being 20/20 I would say one of the providers was a true trained Tantra practitioner and the other two either simply read a book and/or were using the "Tantra" brand to attract clients. Sting is one of the Celeb types who tried to bring the Tantra thing mainstream.
Overall, I would ONLY recommend Tantra to one who has real premature ejaculatory issues or you are a throwback to the 60s Hippie types.
Per my experiences, I was more weirded out than turned on. The provider I feel was the true Tantra practitioner took me through the whole interview process; chakra discussions; ceremonial bath; the breathing, etc.. Once we started the breathing stuff I was like OK WTF did I get myself into?!?!? It got to a point where there was starting to be waaaaay too much talking going on along with the all the breathing noise. I can't fault her as she was doing her Tantra thing. But since I do not have premature ejaculation issues and I'm a "city dude" all the Tantra "gobbledy-gook" was starting to get on my nerve and became a nuisance. I kept fighting my mind wanting my mouth to blurt out..."get to it women....I'm ready to cum!"
My main attraction to the Tantra brand was the anticipated length of the session and the advertised focus on the journey to the destination versus focusing on the destination. However, the journey, for me, was waaaaaaay too long a trip along with it not being interactive enough for me. I'm a hands on kinda guy.
I'm glad I started with an apparent "real" Tantra provider cause it was clear that my subsequent experiences were with Tantra wannabies and, not so good ones at that.
So if you're not into the mystical, chanting type of build up to your orgasm I would not recommend. Of course you can try at least one time just because and to see, if................................
I think you hit it on the head with your phrasing..."that the quality - and even the definition - of Tantra is pretty unregulated." CMTs have standards to meet I don't know about the Tantra providers. So it's a box of chocolates.