Yeah, it really doesn't make any sense, does it? Any idea what to look for as the culprit? I wouldn't mind knowing what the problem was because if it's still present and I've only masked it with the new bridge then:
1. The problem might return.
2. Maybe I can get even MORE sustain after fixing it.
I had it in the shop, tuned up and set up several months before and while the playability improved greatly the sustain was no better. Two experienced technicians looked at it and nobody said anything about cracks or loose joints, tuners, etc, which are the only things I can think of that would cause the problem.
The adjustability is pretty sweet. I've never had string spacing adjustment available to me before.
Next time I pick it up I'll try your test, though of course my results will vary with different strings (and different ears). Thanks for the detailed input.