I’m partway through AN/DP/Helitrox (will finish next year - unavoidable scheduling issues). I used 20/20 for all class dives. I get narced BAD starting about 110ft. The first dives I did were to about 115ft or so. 20/20 gave me an END of 85-80f. OMG. Fabulous. Clear head. Worth every penny of the $4.60/cft ($90 per LP85 filled to 3000). I was diving 40F water. I recommend everyone do recreational Trimix/Helitrox with their deco class.