For my use, I want the Exceptional for sure to be High. If its the success to craft thats high that's great too. but crafting non exceptional and failing to craft and losing some material are the same to me. I would rather have 80% succes to craft and 100% exceptional then 100% to craft and 80 % exceptional. you lose material crafting non exceptional, (because you have to toss it, or salvage it) and you lose material failing to craft. so I look for talis that first give me High Exceptional and then I look at the regual craft success chance. And for grins I throw a few on and double check the numbers, then craft a few items that are harder, (i.e. higher fail rates) and see if one is truly best. As I feel there is some bugs still in your real chance versus what your crafting gump says there is.
Hopse this helps
Cheers,
Xander.