Vintage Vs Modern Pickups...
Are "vintage" pickups really better? Are the materials they were made of really different than the materials of today?
There is a lot of debate about whether the copper of yesteryear is any different from the wire of today. There has been numerous studies that say that copper is copper, but the die-hards will say that it it different. One thing is for sure, the tolerances were looser in the old days because the lasers used today for measurement were not around. The insulation compounds have changed, although this has less of an effect than the actual thickness of the insulation.
In the old days Butyrate was the main plastic available.
ABS was not commonly used at the time the original "PAF" was developed. Does it make a difference in the tone? Not really. It has no real effect on the resonant frequency of the pickup. The size however, is a different story. Modern pickups are usually 50 or 52 mm. The PAF was 49.2mm. This changes the coil shape... That matters.
Magnet type and quality always matters. Does it matter if the magnets were made in the 40's or 50's? Not really.
Covers, Slugs,and Screw Poles
Now we get in to the fun stuff. These all have a marked effect on the eddy currents and magnetic field found in the pickup. The nickel based components found in early pickups are still the favorites today. This does not mean however that copper or brass are "bad". Many pickup builders have designed these various materials in to their tone. The only time use of these "cheaper" materials is a bad thing, is when they are used simply to cut costs.
Many materials that are used today simply were not readily available, or invented yet, in the 40's and 50's when the popular "vintage" pickups were being developed. Pickups built with these newer materials and experimental designs are not "less desirable" than vintage ones.... Just different.
When shopping for a pickup, forget all the buzz words and ask two questions...
Is the pickup I am considering a result of design, or is it a result of cost cutting and compromise?
Does the pickup give me the tone I am looking for?
That .... is what really matters.