Yash, no idea what you're trying to say with your maths there sorry (I'm no math wiz). But my point at it's base is that if you can land the spell then the recast doesn't matter a damn, because you've already landed it. So if you don't have the greatest hit rate, surely it's best to improve your chances of landing the spell as much as possible rather than worrying about a few seconds of recast time. Who knows, that 5 macc might be just enough to get you over the line to make the spell land, in which case you won't need the faster cast time.
Korpg, so by your logic, if you have duelists chapeau you can do all your enfeebles completely naked except for d.chapeau, but if you don't have it, you should put enfeebling magic skill in as many other spots as you can, EXCEPT for the head, where you should put something that doesn't help you land the spell at all.
You are literally saying that without d.chapeau you are screwed, won't land debuffs to save yourself and should let a d.chapeau rdm land them instead. In a HNM fight with no adds, you're half right, you should let the best rdm stick to the debuffs (unless you both have different group 2 merits, and can share that part), however that doesn't mean you shouldn't gear yourself to be able to land spells as accurately as possible. What if:
-The d.chapeau rdm dies/dc's/afks
-You get an add
-There are multiple mobs
-The other rdm is busy when grav/bind/sleep wears
A rdm's main job is enfeebles, and as such you should be geared to land them as reliably as possible, regardless of whether or not you have d.chapeau. If you're not required to at least enfeeble in an emergency then why are you even on rdm? Go change to whm, brd or cor or something. And all of that's just talking about group situations with another d.chapeau rdm. There are also a million and one solo and low man situations, or even large scale events where there will simply not be a d.chapeau rdm, so what then? Should the only available rdm cast in full fast cast gear because they have a low chance of landing the spell? I'll answer that one for you, no, they should maximise their potential to land debuffs the FIRST time, which, (shock horror) may just happen to mean swapping out Warlock's Chapeau for, you guessed it, wise or elite.
But hey, that's just my opinion, and it's how I'll be doing it until I get d.chapeau.