ok i have a few things that i need clarifying on-

1.) difference in sound between neck through and bolt on necks

2.) what are good neck joints for fast playing or reaching the high notes easily and what guitar i could find them on

i know Ibanez's have good thin necks but do they make models that have good neck joints for higher playing?
Their bolt on neck joints are the best for high fret access and they are super comfortable! Usually more sustain is achieved with neck thru guitars. I get pretty good sustain with my bolt on neck though so it all depends on how tight the neck joint is.
My Gear:

Fender Strat w/Duncans
Hand Built(by me) guitar w/Duncans
Ibanez RG321MH
Bugera V22
Peavey Vyper 30 Watt
Xotic BB Preamp
MXR Carbon Copy Delay
Digitech Hardwire Chromatic Tuner
Fender T-Bucket Acoustic
Digitech Bad Monkey