As a little background on myself, I've been diving for 11+ years (originally certified through PADI). About 5 years ago, I went down the non-GUE tech path through TDI and IANTD and did Intro to Tech > AN/DP > Trimix > Intro/Full Cave. When I started down this path, I really had no idea what GUE was outside of a few snide remarks from my instructor.
Regardless, I've done all my training in BM and to this day dive pretty exclusively in BM (outside of a few instances where the cave dictates SM). I'm a very curious person naturally, and so during this period, I talked to quite a few people about DIR, read a lot about DIR (mainly online resources and the Fundamentals of Better Diving by JJ), and was lucky enough to become good friends with someone I would consider a mentor who is a GUE diver and cave diving buddy. So, needless to say, over the years, I've adopted DIR principals and methodology even though I was never "formally" trained in it by a DIR-affiliated agency like GUE.
While that's all and good, the thought of taking GUE training has been growing in my mind recently, even though I feel like I would be going backwards from where I am today. I do really like the organization's training practices and standards (after seeing some less than optimal training through other agencies) and my thought process is, I know I can learn more and continue to hone my skills (which at the end of the day is the most important part to me). I also would love to get involved in GUE projects and/or other affiliated organizations like WKPP (which isn't exclusive to GUE but it obviously has significant overlap).
With all that being said, back to my original question: is it worth taking Fundamentals this late in the game? Has anyone been down a similar path? I know it's an investment of time and money, but the tradeoff could very well be worth it. Would love to hear some thoughts!