A SFP scope can still be useable at different mag settings, just takes some interpretation.
IE, if a SPF scopes reticle subtends true @16x, it will also subtend a whole value angular measurement @ 8x, and even 4x, for that matter. When ya half the mag, ya double the reticle subtension...
So, a 1 moa hash in the reticle @ 16x will equal 2 moa with the scope on 8x power. And the same hash will measure 4 moa @ 4x. Not quite as useable as FFP, but you can make it work. Good way to stay straight is to put a dot on your mag ring with a Sharpie, at ranging power, and two dots at half that setting. Quick way to make a SPF a bit more useable for holds...
Good luck withyour scope choice!