Do yall feel that these could lead to line failure more so than a line to line connection?

The only reason I would use a ring is if it is built into the looping end of a furled leader. Tie your tippet to the ring. Other than that, I would use loop to loop using perfection knots. The less connections, the less points of any line failure.

Probably, but I still use them on my nymph leaders. When I have had to pull leader to the point of breaking off from some obstruction, I have found that the break will happen at the ring about 70% of the time (always on the weaker line connection) and at the fly 30% of the time. The few times I have lost a fish that broke the line the break happened at the fly. I have learned to tie the rings in my den, under a good light, and not attempt to handle them in the midst of a stream.

I use them on every leader I have/build. If competition fisherman use them then I sure as heck am not going to worry.

Turf Dawg - do you use them on leaders tied to dries? I know that the surface tension the rings create should be sufficient to prevent them from accelerating the sinking of the leader, but still have my doubts.

I have used them with dries successfully. No problem with drowning the fly.

I might avoid it in super clear water with very spooky fish, but for generic dry fly fishing it's fine, in my experience.

I agree with Glichmo. I only use the 2mm and never had a problem but seldom fish dries

I use them. Have caught fish in Tierra Del Fuego up to 21 lbs with no issues whatsoever.

No issues fishing wet or dry.