Currently rocking 403 Maw and was wondering if a heroic Vagaries would be better then this, then followed by heroic Maw. I know Vagaries is better on some fights, and Maw is better on some as well, but I mean is heroic Vagaries flat out better, or should I stick with Maw?
Uh, no. It depends on your situation, but in the majority of cases that's incorrect. The heal proc from the maw is ridiculously powerful, and the only time you should consider Heroic Vagaries over Maw is for 10 man encounters where you're very spread out. If you're a 25 man raider you might as well never swap out your Maw, it's just too good.
Also, you could try searching before asking a question like this. I'm sure this has been asked at least 10-20 times in different places of the forum.
Maw is doing 3-6% of my healing, for free. If you have recount or something similar, look at how much healing it is doing for you, and ask yourself if the extra stats will make up for that loss in healing. I find it overheals a fair bit too so it's even more usefull in high dmg phases. All our healers passed on normal Vagaries in favour of RF maw for the proc. I might take HC Vagaries over RF maw once we see it drop.
I'm Holy and I only use Maw when I'm solo healing H Ultra or doing Madness, otherwise it's Warmaster staff for sweet sweet mastery and spirit. I'll probably use 416 Maw 24/7 though if it ever drops, curse you Blade of Unmaking. Under ideal conditions maw is only 5% of my healing and on spread fights it's pretty useless.