It depends upon the landed cost of currently used set retarder Gypsum and cost of production of synthetic gypsum.If cost economics permits then only we should use synthetic gypsum.Handling of commercial grade sulfuric acid is also an unsafe practice and cause of concern.Before making synthetic gypsum at plant level safety and environmental aspects should also be considered.

Characteristics will be same only cost calculations you have to do.If it is commerecially OK that you can save some money.But safety factors also to be considered while using Conc.Acid

Depending on crystal sructure of new gypsum (in this case artifical gypsum) there may be diference on quantity of gypsum for intergrinding with clinker. The only thing yo have to do is correction the quantity of gypsum for normal setting time and early strength  of your cement. There will be no problem with quality.

Davit Babayan