People aren't freaking out about fur coat + 100 defense because having fur coat means you can't be taken down physically, but overheat, fire blast or any strong STAB move coming from a special fire type will be able to either OHKO or do severe damage, which can't hapoen with flash fire. Also, if you can burn the fur coat variant, it is easier to take down as long as it doesn't run recovery (as heal order, for example).
An offensive one with flash fire can run super fang to halve the HP of every non-ghost target, get a 30% chance of flinch with iron head, high critical hit ratio with attack order, and either run heal order in the last slot for recovery in sets that do not invest much defensively, or defend order in sets that are interested in becoming as bulky as possible the sooner the better. In this regard, the fur coat variants can invest in attack and special defense, while the flash fire ones don't even need to invest in any defense whatsoever: 252 atk EVs with adamant nature and maybe life orb considering you can run heal order and use it when needed, and you have a terrifying wall-breaker that is a wall on its own, with no weaknesses and that cannot be burned, poisoned and all that can set leech seed suffers against attack order, and everything that can set up in front of it gets 50% of its HP out thanks to super fang... it is stronger than Eelektross, that's for sure.
I run a flash fire mega scizor in balanced hackmons, and you know how often is it taken down? aproximately once every 8 battles. Basically if the foe is not setting up or has some major mold breaker fire, flash fire scizor just can't go down without setting its rocks or defogging. That's similar to this.