The more wood you have on an instrument and the greater it's contact is to itself, the better the sustain "the notes ring out longer naturally". With modern electronics and amps this isn't too much of an issue though. Dimebag Darrel Abbott for example used some bolt on guitars but he had that amazing scream from them still. A delay with the right settings allowed his to ring out forever. What I believe is more important is that your dexterity and comfort are fitted.
I think bolt ons scream just as well as set-necks if the neck is fitted well. Maybe better. My Stratocaster is a lead guitar monster when I want that kind of sound and that kind of fender neck feel. I think Dimebag is a bad example to use given the extreme amounts of gain he used to achieve his sound. it is a viable signature sound in his genre, but its a very genre specific tone that relies heavily on processing. Even in lower gain sounds, its not fair to use Def Leppard with their racks of gear when advising someone who is sharing a budget tube head with his buddy what guitar to choose to get a nice, full hard rock kinda lead.
Myself, I like to let my hands and the wood do the work. If the amp exhibits some nice natural compression at all levels I'll take it, but otherwise I just want the thing tog et out of the way and to either provide overdrive or not. But I am a vox guy in the Brian May sense of vox.
I prefer 2 options on all my instruments that lower the sustain. I like bolt on necks so that I can easily replace the neck if something happens to it (twisting is an issue in dry Texas weather) and I like super skinny necks. I'm 6'3 and 310 lbs. My hands are large enough that from pinky to thumb is 9 inches. Most people try to throw me fat necked instruments and I cannot stand them. My fingers bend in towards the center of my palm when I bend them, so making large stretches on a neck is not an option for me. I also have a death grip on my neck when I play. A larger neck makes my grip weaker and I feel some techniques become harder for me to do without a strong pinch.
Interesting about your hands. I have very straight, very thin, very flexible fingers. Also while my hands extend 8 inches from palm to middle finger they are MOSTLY middle finger. I also do not grip the neck hard unless I a annoyed with the drummer. I have a super-light 'grip' that doesn't 'grip' really at all. I kinda float. Jazz background. I love bolt-ons... own 3 good ones... they are way easy to work on... but if you maintain your set-necks well they last forever too. I have never needed to straight-up replace the neck on a bolt or had a Gibson become unrepairable. And I have lugged both types of guitar on tour through all sorts of climates in vans or hot trailers!
Something I shoulda said about gibsons is that for some reason their headstocks are prone to snapping off if they are dropped or hit. I hate this tendency because Gibson clones (other than epiphones), guilds and gretches... hamers and PRSes? don't do it unless you are really trying to bust them. I don't know what it is. SO that's Gibson's big downside for a guy who likes the encks big, wants buckers AND isn't opposed to a set neck.
I think in closing, that thing you said about lots of wood causing notes to ring out longer? If its lots of resonant wood that acts as tone filter the notes ring out longer and more musically. Even on a fully solid-bodied instrument. I really find that the better a guitar sustains, the louder it is and the more interesting its sound UNPLUGGED? The better it sounds plugged in. You can't put harmonic complexity back in. Everything about a guitar is a physics experiment in loss of energy.
