I love my fulldrive2 MOSFET. I use it with the mosfet switched on and the other switch in vintage mode most often. The boost isnt much but it definitely does just what it says. I will typically have the boost set pretty far over clockwise and will use it when I'm playing an already crunchy part and the next part needs just a bit more oomph. The boost is not like a whole other gain stage, it is just a bit more what ya already have. Great pedal that plays well with both humbuckers and single coils.
diff'rent strokes for diff'rent folks