I’m curious, did you read the PTR patch notes? While I wouldn’t say for sure that they’ve hit the 400% damage increase you’ve suggested, the new Aspect that triples the beam along with all the other buffs they’ve piled onto it since S2 probably gets you close to that mark. At the very least I would expect it to be much better against bosses now.
I think the consensus is generally that it still probably isn’t enough to make the skill shine (which may simply be impossible without a fundamental rework of the whole thing), but I imagine the damage now is substantial. The forced immobility while channeling remains the skill’s Achilles heel; my opinion is that once mobs start hitting hard enough to one shot a player, Incinerate will be fairly ineffective, but up until that point it’s probably going to be alright, possibly even good.