I would strongly advise you to back off the "best mix". People have toxed at that depth on similar mixes. Pushing ppO2 1.4 on the bottom saves you at most a couple minutes of deco. Check out this tox incident from July 14, 2007 in FL at a cave called "the crack". You will have to scroll down and find it by date.
Incident List - IUCRR
She toxed at minute 31 or 32 on 24/26 ascending from a 160ft dive. She died. (coincidentally she had planned on using 80% as well but didnt survive to use that). She was well within CNS limits, but there is some speculation that trimix exacerbates (or doesnt ameliorate O2 toxicity to the same extent N2 does). Pushing trimix ppO2s working/swimming on the bottom is bad news.
Best mix thinking (for me) comes from that recreational thinking to get most bottom time within NDL limits, then you get the tech training and (exaggerating this) you could care less about NDL's. Also, in the Great Lakes area where there's more custom mixing verses banking, I'm sure best mix is still pushed - regional thing.
The Heliox class goes to 180', so 21/35 has a po2 of 1.4 at 187'........ Get's you thinking
Really strange accident report there - seems nothing odd at all which is scary spooky. You got any reading on that higher PO2 and Helium line of thinking? That's just really weird as don't the CCR guys try and stay at a constant PO2 of 1.2 which would expose you more than a brief stint above 1.4........