I agree with most of the people in this thread on both arguments to be honest. Steady hand is fine as it is and losing usage is part of the synthing strategy.

I also agree that you should lose all your mats if you cancel a synth, it's far too easy to abuse otherwise and even a chance you will get your mats back can and would be abused by some. It really isn't hard to avoid the DF while crafting situation, I always craft or gather while waiting on DF and I just bear in mind it could pop at any moment and play accordingly. I don't start leves (gathering) or start any HQ synth that requires concentration while DF is searching, if I forget (which I have in the past) then I skip the dungeon and wait for the next one, I can only blame myself for the extra wait.

Disconnecting while Synthing I'm sure would be frustrating but it's hardly going to be a common occurence and it simply isn't worth making aspects of the game easier to abuse in order to ensure people don't lose mats in such cases.