Re: clarification
Tightness or focus is more of a feel than a tone issue, at least thats how I perceive it. Alnico II magnets tend to have a softer, spongier attack somewhat simular to punching a pillow. There is some give in the attack and a somewhat vowelish character to the tone.
Ceramic magnets tend to have a very agressive and angular attack, more simular to punching a wall. When your fist hits the wall, you know it. There is no lag between the pick attack and the development of the tone.
Alnico V magnets are somewhere in between.
It's really not a warm or bright issue though and a Pearly gates pickup will be brighter overall with a softer attack on the bottom, while a Custom will be darker sounding with a tighter bottom end. The 59 will be brighter than a PG but will have a tighter bottom end. It's a combination of magnet types as well as other construction issues that will ultimately determine the agressiveness of the attack as well as the overall tone.