I personally haven't completed too many tasks (going on 27 I believe - so I have 3 blacklists and a few spare points), but I looked into it and it really doesn't look like all that good of an investment. Yeah, sure, I will probably go out and get the ability to make it after I get off my 4th blacklist, but until then, I could care less. There are really only three tasks that need special headgear: banshees, abberrant spectres, and dust devils. Banshees and abberrant spectres are undead, so a salve amulet (e) + the special headgear would be better than slayer helmet + fury. I'm not saying the slayer helmet wouldn't benefit against banshees and spectres, it provides slight more defence bonuses and it makes you look cool. That leaves dust devils, and I am not spending 400 points to benefit one task when I can eliminate four tasks. Then there's the defence bonus. If you are getting hit so much during a slayer assignment that you think that a defence bonus similar to a rune full helmet will significantly help you, maybe you should reconsider what slayer master you are using. Convenience is also included when you get a slayer helmet. You have all of the slayer headgear packed into one, so you could go straight to dust devils or abberrant spectres from Sumona. Although, I prefer to bank and get out the proper weapons and inventory to kill those. I s'pose you could use the magic carpet to the Shantay Pass and back, but it isn't providing the motivation to get it before blacklists. All in all, it is benefitial to get, but it should not be your #1 priority of Slayer rewards.