a SFA has the advantage that it maintains grund clearance. If you hav 10" at the pumpkin, you always have 10" at the pumpkin. With IFS if you put one wheel at full compression (say on a rock) while the other wheel is at normal ride height (on trail) you can lose up to half of your clearane at the pumpkin since the one wheel moved up while the other (and the pumpkin) stayed in place (relatively). This may not seem like much, but if you have 10" of clearance and need to straddle (for some reason, work with me here) a 9 1/2" rock and you lose clearance at compression, you'll be having some issues.
Justin