There is nothing wrong with bolt on necks. The dovetail neck joint was a great idea when guitars were being built with hot hide glue, but some (especially in the hand builder world) wonder about how good a dovetail neck joint is when aliphatic glue is used. Theory is that the aliphatic glue (basically the white wood glues that are around, Titebond being a common one) never really harden up completely, always being somewhat flexible. Due to this, some string energy is absorbed by the aliphatic glue vibrating, which takes some of the string energy away from the top. I don't know if this is even audible, but the basic concern seems valid.
Years ago there was a thread containing a ref from Chazmo about New Hartford going to Titebond for neck sets, due to faster set up time.
The tone thing wasn't brought up at that time but what
was brought up was what you mentioned about the strength of the glue itself.
ALL glues have a "creep strength" rating, think of it as "stretchablity" and hide glue has the highest creep strength rating of all glues suitable for woodworking use.
Basically it
don't stretch so it's the best thing to use in setting necks.
I found it interesting that within a year after that coming out we had a couple of reports of a couple of New Hartfords (one a 12-er) exhibiting signs of premature neck dive.
My personal belief is that optimum transfer of vibration between neck and top via fretboard extension and heelblock is with a glued joint, hide glue being the best transmission medium due to hardness.
You just have to feel the neck vibrating in your hand while you're rocking out like Richie Havens sometime to be a believer that it somehow helps tone and volume.
In fairness I have to admit that I'm willing to try out a bolt-on without prejudice, especially since Guild saw fit to experiment with it themselves, but I also note that they supplemented the bolt-on neck with the "spider" tone-arm attachment to transmit extra vibration from the heelblock to the top.
That could imply they were aware of that phenomenon and that a bolt-on might need the "extra assist" for volume but it could also mean they were just trying to "up the game" and it worked better with the graphite heelblock.
