I don't know about craft, but I disagree that FSSA breaks the sorcerous working system. Not for Solars, anyway, who can already reliably complete Finesse 5 Ambition 3 Solar Workings with very little chance of failure or need for extreme measures. It doesn't allow them to do anything they couldn't already. It just saves a few weeks of time, cutting the number of intervals required roughly in half.
Just going to stop you right there, because I think you missed something rather critical:
you only get 5 rolls by default. You don't have the total by then, you fail. You increase that by increasing Means. So given your later math of 10~ successes per roll? You don't finish by about 25 successes.
Given your supposed to get around that by acquiring Means, and not buying Larceny Charms (which have no link Sorcery in the slightest, why are you being incentivized heavily to buy this) I fully stand by my statement it breaks that system. Actually, given the whole 90% of your roll thing, a Supernal Larceny character can get ~21 sux per roll, which easily lets them push for Solar Ambition Workings at E1. The time scale is obscene (one year per interval), and its a +4 to difficulty on top of the usual Fineness difficulties, but it shifts it from 'haha no' to possible, which is so very much not the intent of the system, especially with fucking Larcerny.
So yeah,
it breaks the system, in that the system no longer functions as intended, and in that it makes the optimal path to invest in Larceny. Which, for an Occult based system, counts as not functioning as intended.
It really does amuse me that the labyrinthine probability interactions that were explicitly intended to make it impossible to judge exact chances and to make things more a case of "more dice is better"... didn't work, and people are analysing the probabilities anyway.
*Shrugs.* I strongly suspect we are going to see the sort of analysis's I've been doing on and off published into the game line when the Exigents comes out. If nothing else, even the preliminary work I've done for an Alchemicals conversion shows you really do need this stuff when homebrewing a full up splat. If you don't know what you need to succeed for a given level of Artiface Crafting, how can you design charms for Crafting?
It doesn't really surprise me this isn't in the Core either: there's a lot of it, and they're already having size issues for the Core. Exigents is the logical place to put it, really.
They're really not even all that labyrinthine to be honest.
It really wasn't. I mean, I had to check with some of my more math inclined friends to make sure I understood things properly, but once I got that it was mostly 'adjust formula, run through calculator and check anydice to make sure everything checks out'. Most of it was just finding the time to sit down and run the numbers.
Course, the 'understand things properly' was a not insignificant step. Thank god for the internet and math inclined friends!