I use the same NVG's. I have never had a fog problem, and I look at them for a long time. This is on Fp-4, Hp-5, TXT, TMX, TMY, Royal pan, Formapan 200, J&C 100,pan-f, verichrome pan, APX25&100 (haven't tried it with IR film).I don't have any problems with light leaks either. When I had a fellow Ape hugger over to have a look, I saw how the leaks happen. When looking at different parts of the neg he was moving the unit not his whole head with it. This was pulling the unit away giving the side leak. Developing in pyro has a secondary benefit, in that it is desensitised quite a bit by looky time.
I still already know what time and temp is for a film. The nice part, is I don't have separate plus and minus developing boxes to store film in till development. If I have one that was over exposed for under development. That will show up right away as more density in the bottom sooner. How long will it be developed? It will be developed to the plus factor previously worked out, with DBI for fine tuning. If your thinking about using DBI so that you don't have to do all that film speed testing, and all that other mundane boring crap. I recommend, for consistency, that you take your film to Wal mart.
I jumped on the DBI with NVG in the beginning as others here have. I am willing to bet any one of them still develop for a worked up time and temp, with DBI for fine tuning. Best part is when you can save something in the middle of the development process. (How come the notch on the film doesn't match what I KNOW FOR SURE I loaded into the holders?)
Watch the film as the first density appears. That is where you will look to decide when to pull. Film size doesn't matter, I did some 35 yesterday. It is easier, I admit, to learn on larger format. The particular point I am using to decide when to pull, usually fits well within a 35 format area.
In the end, are they worth it? I have yet to hear, even one, who has tried them and didn't think they were worth it. I got by without them for over 30 years but, wouldn't want to give them up now. They are not a silver bullet, but I bet some will agree with me, that it is a pretty shiny bumper though.