Hey Dan,
Thanks for all of the detail - TBH, I don't know that much about it myself - I don't even know what "Essence" electronics mean compared to the other options, and even after owning this bass for 12 years, these comments were the first I even knew that there are different electronics packages (I don't think I ever read that card until a few days ago).
I first saw this bass new in a display case at Guitar Showcase in San Jose, CA in February 2005. I was looking for a 5 string bass, but had no specific one in mind, just needed the lower notes for a particular studio session I was working on (at the time I was playing a '64 Fender P-Bass, though I had owned an Alembic in the past - an Exploiter I bought in the early '80s, which I bought from Tyran Porter of the Doobie Brothers - you can see me playing it in this 1984 video:
Anyhow, $3588 later, I had the bass, and it just turned heads in look and sound. I had to give up the '64 P because I kept getting confused switching back and forth (first note of a song could be quite embarrassing if I wasn't paying attention!), and it just sounded so good on everything, I only needed the one bass for the next 12 years. That should help with the answer to the "downside of a Q-Switch" question. Basically, my ignorance about my own bass comes from never shopping the options - I took it out of the display case, played it, and couldn't imagine anything better!

The reason I am (thinking about) selling it? I'm just not playing that much anymore. I have had a great career in music as a recording engineer/producer, got the Grammys and Platinum records, and after long days of that, much of the time the last thing I want to do is more music (sad as that sounds, but it's not - I am very musically fulfilled, working around the world, with mostly A Cappella groups - another reason I can't whip out my bass and join in!)
Weight is 10 pounds, on the dot.
Measuring from string center on the bridge, 17.5mm
I don't understand the question about tone range relative to set neck...

I never adjust anything, but I also live in California, so there isn't a lot of weather change.
Neck dive - not in any practical sense - it is enough to lightly pull on the strap, maybe, but if I let go completely it still says put.