The '51 I've had for a few weeks, gigged it several times. The sdbc-3 is big fat and authoritative. It's nice to mix in some of the J pup to round it a little. The pots are now vol/vol instead of vol/tone. I think the flats will calm it enough I'll be ok with that...but if not, it's a set of 60's re-issue Jazz stacked pots for it.
The Jazz is nice! A really good combo of fat lows (for a Jazz), and snappy but not to bright or grindy highs. At the job I played Friday, I played thru a TFB420 and Schroeder 1210, and it was fat and clear till you dug hard, or snapped on the strings a little, and then the birghts jump right out without that "70's Jazz Marcus Miller brilliance" if that makes sense. Which is fine with me, because I like the older sound better for the jazz, blues, r&b stuff I mostly do.
My opinion: the MIJ stuff is every bit as good as the MIA stuff, and I've owned lots of that, and still do.
Kind of a Fender-a-holic I guess!