This still requires 60s between you pressing the Infuriate button and the trash pack you're killing to die, which shouldn't be happening. If it does, your group's DPS is massively slow or you're pulling for a full minute. On the chance that does happen, obviously using Infuriate is good though saving it for the boss could be better, depending on the situation (mobs will probably be low, will probably waste damage on a SC when a BLM is casting Fire2 or w/e anyway).
My point about maximizing AoE dps was mainly for when the group consists of low AoE dps like monk, sch and smn. If you have a high AoE Dps comp like double BLM + WHM or BLM WHM BRD then don't waste unchained at all because the mobs will be dead before unchained wears off regardless of your damage. Save it for the boss instead.

Not sure if 2% extra crit outweights the benefit of having 1 extra Unchained buffed OP, but that's sort of splitting hairs anyway.
You lose a fully buffed overpower and replace it with a fully buffed steel cyclone at the end for more damage + healing. Again, only needed if you are in a low AOE dps comp.

The reason Flashing isn't ideal is because for those 2 GCDs you spent Flashing for no damage, you could've gotten up Maim
You get maim up to refresh your stacks, and you always put it up again as you are approaching the last pack. The first thing you do when everything is in range is a fully buffed overpower so you lose no time. You flash the rest so the dps can start getting dps rolling before the end of the pull, monk can start building GL and healer can drop cure/SS/Adlo whenever they like with no risk and it's easy tohit all of the upcoming group with it. If you just HS > maim you are gonna have a lot of unclaimed mobs coming after you. I hate having mobs chasing me that I have little to no agro no. It's an accident waiting to happen. The healer should always feel safe enough to throw out a cure/regen without peeling mobs off you mid pull.