What makes those pickups "better" than those in the mid-priced category that use the exact same materials??
I’m way over the whole “let’s buy a $300 guitar and spend $400 on parts” stage of my life.
When I first started playing, “upgrades” never occurred to me. Parts only got changed on guitars amongst the players I knew if something broke.I think that's a common mistake people make when they get "upgrade fever". While it happened before the internet, online discussions accelerated the process of people spending a lot on upgrades, many of them unnecessary. And, as some recent TDPRI posts indicate, it not only affects cheapskates but people who buy custom shop level guitars.
My own philosophy is to look for value, especially gear that's undervalued or underappreciated. People often almost give away great parts because of some perceived flaw or just fickleness. My problem is that I end up with a lot of parts I can't use right away but I might some day.
My understanding is that Ron, a materials expert, tests every single component that goes into every pickup. He has access to a high end materials lab, so it's not test equipment you can get from StewMac. Every magnet, the wire (which apparently changes diameter along the length of the spool), and the base plate. He rejects a lot of those "exact same materials". He also has studied the early pickups--you know, the ones we worship, to see what made them tick. He was involved in the writing of "The Blackguard Book".
What I take from this is that if you get a really good inexpensive pickup, it is luck. Ron Ellis is able to reproduce a really good pickup every time, and Ron winds every pickup himself. That is what you pay for.
Perhaps what was different about this particular Epi Jr was that it was part of a GC special run with a few differences from the regular ones. Its P90 is about 7.8k ohms while newer ones I've measured from more recent P90 equipped Epiphones were in the 14-15k range.
You may have a point about some stock pickups on some lower end guitars being feedback prone at higher volumes. I have noticed that there is a trend towards hotter pickups in lower end guitars. I guess that's an effort to make them sound better with inexpensive practice amps. It used to be that cheap guitar pickups were really weak, now the opposite is more likely.
But I don’t recall one person ever back in those days buying a guitar and changing out the pickups.