I didn't do a ton of A-B testing as I didn't want to ruin the stock pads by constantly swapping them, but I feel like treble is at least as prevalent with the ZMF cowhide pads. In fact at first I thought there might be too much, but I got used to it. There is a little cloth insert behind the regular pad that I also removed when I put the ZMF pads on, so this may have something to do with it.
Even without having heard the SDJ, I completely understand where you're coming from with the SP sounding congested... That being said, the new pads GREATLY improved the SP in this regard and brought it to a whole new level.
I still do want to hear the SDJ, though. :P