You suck at math.
4.3 mil to 8.6 mil is a 100% increase, not 200%.
Anyway, a bit more fine tuning is needed imo. The initial 10+ mil was so unrealistic.. I know it's a hardcore server but scaling up the health of a dps race boss over one of the toughest bosses ever made by blizz (Algalon) is just ridiculous. A 50% increase would be just fine. You're forgetting that with all working mechanics, spells, etc. blizz tuned it to 4.3 mil. You can never achieve blizz conditions.
If you start making ridiculous numbers at the begining, you'll end up like blizz did with MoP and tanks having 1 mil hp.
Imagine it.. if you scale bosses by 100%, then for example, Algalon 25 will have 60mil+ hp. He's already a hardcore boss on his own, with a 6min enrage timer (take away the big bang phases). So by going with this logic, you'll need 10 mil DPM from the total raid. If you have 16 dps, that means each will have to pull the amount of dmg they're pulling right now in RS25 with 6.3k GS for example.. and Algalon is just the optional boss in the 2nd tier.. Imagine the **** ups later when you reach the 3rd tier in WotLK and you have 4 separate modes.. will Lich King 25hc have 206 mil hp? Will Festergut require 105 mil damage done before the enrage timer ticks? (5min enrage)(needing around 20k dps)..
A lot of things need to be taken into consideration, not just slapping a number and then nerfing it. That's what blizzard usualy does, but in early private F&F alpha tests.

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