Ok, so if class is simply a forward declaration (and potentially a UE4 convention) then that is really straight forward. 
Knowing that TSubobjectPtr will be removed in 4.6 means I can continue to use just TSubclassOf, otherwise it’s just a pointer. I was further confused by the terminology in blueprints where passing an instance of a class you pass an “object” but if you pass the class blueprint (if you will) then you use “class” as the parameter type, but I think that everything makes sense now.
Appreciate the help.