I still don't see the point of them outside of raiding. In dungeons it's not uncommon to get tanks going for tri-pulls, in which case they're running from the start to pretty much the first-boss doorstep (unless obstacles prevent this). If they're even considering this, they either have faith in the Healer or know their gear/limits (preferably both), to which I'll wait till they're rounded up (casting AeroIII's along the way), Asylum/SC-Holy, re-apply AeroIII to the entire pack if needed, then rotate between top-ups and damage depending on how squishy they are.

Pre-pull regen may tick off some of the auto-attacks but at the cost of something possibly breaking expectations eventually, be it due to tank negligence (some would tell you off for pre-pull regen -- after all, it's historically a no-no, no matter how 'right' it may be in other circumstances) and others probably just won't expect it. Bit different if people communicate or already know eachother, not so much with randoms in DF who go from A to B entirely on assumptions.

I'd much rather a 100% guarantee the tank doesn't have to deviate (because I can cover anyway) over taking the risk for the sake of not having to spend one GCD later on. The only time I even use Tetra is when (unrelated) DPS are eating mechanics like plebs or a) the Tank is pre-pulling and I'm intentionally waiting for them to get comfortable or b) as a 'just in-case' when I'm DPS'ing during said mega-pulls.