I was about to suggest that. Wouldn't it solve the matter, without killing SFs?
Though, to be honest, I have always disliked SFs and their lack of definition (people RP them as anything, mostly as better soldiers of the other types).
They mostly ARE better soldiers of the other types. They aren't something like Navy Seals
We have always had freedom with how we RP our units. I could recruit men from the same RC as you, but RP they are pikemen wearing mail, while you decide they are axemen wearing brigandine for example.