For known distance target shooting where you never touch the manification dial, SFP is fine, maybe even preferred, since the reticle does not get thicker when the magnification goes up as with the FFP. Your reticle, be it MD or picket fence, will give you a consistent reference for windage corrections.
For shooting varmints or what have you at any given variety of distances, the FFP really shines. No matter what magnifiction you are at those 2 MOA hash marks are always accurate. No math to figure out how far apart your mil dots are at ather magnification settings.
I have the 6-24X50 MOA FFP on my T3 varmint .223 and I love it.
I don't find the thickness of the reticle undesirable at 24x when plinking at 10" rocks at 1000yd. The FFP lets me pick the manification I like best and focus on doping the wind instead of doing math or relying on memory for wind hold values. Also when putting my first shot out there at a 700yd target and seeing it land high, I can reference the POA vs POI with the reticle and dial in that value rather that guess that it was 18" high and do the math to figure out how many clicks to correct.
It's a nice scope with very solid feeling clicks and good glass. The side parallax works well as does the illuminated reticle. I learned to set the illumination to the off position between 1 and 2 so if it gets bumped on it won't kill the battery so fast. I went through a couple batteries that way.
For me the FFP was definitely worth the extra $$, and the scope was worth the 10 month wait.