Gosh, I wish I'd have done an A/B for y'all, but I guess I was too far down into the project to think about anything but getting it done without screwing the pooch. However, I suppose I owe anyone who was interested at least a follow-up:
I never did pull the whole thing out. Matt wrote about the nightmare of trying to remove the whole pickup system from the guitar, so I opted to just pull what could and tuck the rest inside, securing the wire back on itself over a couple of the little hooks. So far, no unraveling or flopping or other nuisance. I will say I'm delighted by the improvement in sound. With such a big ol' top on this guitar, it defies logic to think it wouldn't have made any difference and it was immediately apparent.
So I thought, heck--since the bone saddle made such a difference, let's go with bone bins too! That turned out to be a disaster. Maybe it was the inexpert way I sanded them down to fit the holes--I don't know--but the sound was jarring and absolutely awful. It was if each string had a mind of its own and all six of them were pulling in different directions, sonically speaking: jangly, noisy and harsh. I immediately put the plastic (Tusq, I guess) originals back in and the problem vanished. (The originals look a lot cooler, too!)
So if anyone happens by this post and wonders whether it was worth it to pull the under-saddle pickup out and get a clean-bone-to-wood connection--well, it sure was for me. Clean, dry Mahogany pop and growl. (Never weighed out the difference, but even with the pickup inside, this big guitar is incredibly light) I bought the SJ-100 as a second guitar to my main Martin HD28, but now the Gibby's getting far more play and has been for some time now. Love, love, love it.
Thanks for all the help,
Googster