I like the concept, having an extra 100% slot would be very valuable with for Grade 5 materia melding.
Alchemist specialist would have to have the potions last longer (like 3 seconds) or have a shorter recast timer for to be valuable.

But, this still leave the Armorer out in the cold due limit desirable utility of what it can craft. There are only some many Frying pans that can be made.
Now, if they made such changes are being discussed here and created balanced desirable crafts across all the DoH classes, this would have a chance.