Interesting you mentioned Waterbury's HFT. Actually my obsession with rings came from his latest HFT training program (essentially targetted ring work for a muscle group every day).
He's blogged about how rings/paralletes match (and even surpass) barbell loading and is convinced that had he trained himself and clients with rings earlier, upper body development would be way better than having gone the iron route.
I gave his program an honest go and got good results but it's hard to really assess whether its "superior".
Cognizant that his ring emphasis may primarily be marketing, it's still interesting to see old timers do gymnastics/use rings in addition to barbell training. Gives me more conviction on a mixed training style for physique development.
CT's stuff aligns more with grimek, dezbo tan, o-lift obviously but he's always experimenting so it's cool to hear his take "having tried everything" and to see what works optimally.