My question is: Should certain class specific gadgets be more powerful than others?

Personally I don't really know the answer, there are good arguments for and against staple gadgets;

Having "OP" Staple Gadgets improves class identity, Heavy is the destructive class with the RPG, Medium is the supportive class with Defibrillator, etc.

Not Having Staple Gadgets provides more variety in gadget selection, you might feel less restricted with the gadgets you pick if everything is equally viable.