So here's the issue.
I've been told by both Dave, and by a "reasonably" well known local gtr player that F-Space/Trem-Spacing changes the sound of the pickup. Mostly for the worst....
I've noticed on my Charvels that the Duncans in the bridge position aren't Trembuckers. Although I've measured the pickup cavities and a trembucker could easily fit in them. Which is making me wonder if maybe the whole spacing thing is even an issue at this point?
So. F-Spacing & Trembuckers are completely pointless at this time? Only useful maybe when using lower-output pickups? They have different tone than their regular-spaced counterparts, which allegedly is for the worse?
Discuss. Unless you're only playing 7 string gtrs. Then move along, nothing to see here.
I haven't personally experienced any sonic difference between regular and F-spaced pickups, either in terms of physical differences in the pickups or in the pole pieces lining up with the strings. It's never made an iota of difference on any guitar I've owned. As such, I tend to buy the regular-spaced pickups just because they are more readily available and will work in any of my guitars.
The one time it made a difference for me was on an old '80s Carvin LB50 bass. Carvin was using guitar-sized humbuckers on their basses at the time, and the E string didn't have much balls because it sat well outside the boundaries of the pole pieces. The solution for most people was to retrofit the old EMG-HB bass pickup, which also is guitar-sized but has blade pole pieces that extend nearly the full length of the pickup.