you cant really compare FMIC vs SMIC due to many reasons. the biggest reason being theres so many diff cores out there. some will flow better than others, some cool better than others. so unless u test all the fmics and smic cores avail the test would be inconclusive
if u had 2 identical cores(same pressure loss), the smic would give u some more low end tq due to the short piping run (if its run in a proper fashion), but its going to heatsoak faster than a fmic due to its craptastic placement.
so in a nutshell as everyones said. in low boost the smic is great for an upgrade, while it heatsoaks faster than a fmic (slower than stock smic), the short run of piping and better core will give you more hp and better low end tq. If your boosting over 10 psi or need to cool the charge air more, you need a good quality FMIC(or equivelent), no exceptions, with high boost you need to get the temps down, and you need ot be able to cool off your core to do so, even if the piping run is longer.