I find it the scooped setting very usefull live regarding that it is already mid heavy, the f-series.
I would also think that, the best mod for the f-series would be
1) a pressence pot...again, the contour mode also alters pressence but prefixed...
2) a push-pull parallel to series pot for the loop. I find the trick of engaging and driving the tube buffered loop to be very staisfying in low volumes but I would like to have the option of a series loop.
3) If I 'd put an eq pedal in the loop I would probably use it in the first gain channel. Just to mimic the effect the graphic eq has in the regular mark amps, dc's etc. All in all in the contour mode you already have a GEC but what works is personal and many people use the mxr 10 band in the contour mode with great success. I never understood how it works with the parallel loop without muddying up the sound. I find that it does. Hence the need for the serial/parallel mod.