no offence but i get the picture now on the set vs bolt on neck now ;)
Its really very simple
A good set neck is a good join. That would be wood:wood, minimal amount of glue.
A good bolt on is a good join. Wood to wood, tight (as in, in contact, has-to-be-pulled-out-of-the-heel-doesnt-just-fall-off) contact
A bad one of either is also bad.
And all points in between.
Not "one is as good as the other" or "one is as bad as the other" because in any given comparison between the two a set could be better, a bolt on could be better, they both could be equivelent and be cr@p or both equivelent and be good.
Shall I draw a picture. Cos I can and will illustrate this graphically.