Flawless Synthesis would have a use, possibly like you described.... if it didn't cost 15 CP. The CP cost more than anything totally kills it for me. Also, it has only a 90% success rate. Basically, it's the exact same cost and success rate as Standard Synthesis, but a) is a specialized class skill, and b) gives less progress in 99-100% of cases. I guess it's something semi-useful before you get Standard Synthesis and are doing elementally aspected crafts, but how many of them are there at such a low level?