Alchemical exalted have an array of 'extra' charms compared to other exalt types. One of them in particular is evading my understanding. You pick it for an attribute/ability pair (say, strength+athletics or wits+awareness) and when rolling that combination you treat that ability as if it was at its maximum. (So, if I have wits 5 and awareness 1, then any wits+aware rolls I make are treated as if I'm using wits 5 and awareness 5.) The two major downsides of this are A. you can't use this rating to qualify for charm prerequisites, and B. this only applies to the one pairing. (So, if I wind up having to roll Perception+Awareness, then I have to use Awareness 1.)
My question is, can I use this to get cheap ranks in craft skills? Buying a charm costs alchemicals 6xp (plus 12xp for the charm slot, which is generically useful) and buying a skill up to 5 costs 27xp* so if I can do this, it's very worthwile. I can't find any charms that require craft as a prereq so A isn't a problem. If I needed one, buying a single craft skill up to 5 isn't too harsh. (Craft is subdivided into 5ish different subskills, but you only need one to qualify for charms.) It's very rare in my experience to roll Craft with anything other than Int, so B won't be a problem.
I'm planning to play a techie focused character who's hoping to have decent ranks in all craft skills plus maybe some of the special ones like Craft(Magitech) so we're talking about at least 45xp difference here. If I can pull this off with no repercussions (other than my Storyteller smacking me with the rulebook, heh) then that's awesome. If there's repercussions that I've missed (A max on simultaneous charm slots? An important time when you'd roll another attribute with Craft?) but this will work, then information on the drawback is useful. Then again, this might not work for some reason I'm overlooking.
Summarized question: Is using the sixth excellency on every single craft subtype legal, and if so, are there drawbacks? If it is not legal for some reason, why? (And while it's not the main point of the question, if I've miscalculated and purchasing the ability points is cheaper than purchasing five slots+excellencies then that's going to get at least an upvote. I doublechecked the calculation, but that's not to say it's obviously correct.)
Bonus points for factoring in optimal spending of points during character creation, which uses a slightly different economy than during play.
*3x for the first point, then (2 times rating)-1 for each additional point. (-1 because it's favoured.) 3+3+5+7+9=27.