Ok!!!!
Last night, I pulled out the Nickel 57 Classic +, made a hole in the braid and drew the + conductor out through the side of the braid to give me two conductors. That took more time than the entire swap. Wonder why Gibson doesn't do this at the factory like Duncan does on their two conductors???
A big thumbs down to Gibson for sending me slotted adjustment screws too.
Anyways, I pulled out the Burstbucker Pro (a local chum is waiting to try it) and gently bent the legs on the 57 Classic + so it would properly orientate with the string angle. Prior to install, I measured 9.03kΩ @ 79°F. The lead on the 57 Classic + must be over a foot long, so I coiled it into the narrow channel in the pickup cavity. I measured the neck pickup too - also a Burstbucker Pro in Nickel - and recorded 8.05kΩ @ 79°F. I figured I could change out the Alnico V in the neck later on.
My install is the same on all my guitars: Bridge 2/32" bass side - 3/32" treble side.
The 57 Classic Plus had almost identical Ω numbers to the BB Pro it replaced, but let me tell you...it's so much rounder and fuller sounding. the individual note articulation is amazing and the overt brightness on g/b/e is totally gone.
But there was another surprise....the two pickups together really have an amazing quality. there is not a hint of muddiness and leads can be played in the middle position - something that never produced a real "quality" (definitive, articulate) tone for me previously. The combination really is impressive.
I am happy to report that overtly thin, buzzy/hummy character of my last 57 Classic's surely must have been a factory defect. These pickups in my fully shielded S-G are totally and completely silent. No noise whatsoever. Laying a cell phone on the guitar and calling it does nothing. the same test drives my un-shielded 2016 Gibson Les Paul nuts!!!
The copper works....and so do these 57's.
I'm running quite a bit a gain and a very dramatic EQ and I can dial up a lot of bass and still have a full edgy tone with plenty of mids available to stand out in the mix.
In summary I would say the 57+ has a much fuller tonal palette, without the brightness the BB Pro Bridge displayed - especially on the 'g' string - which was almost harsh unless I rolled the pole piece down flush with the cover at the expense of output. On the 57+ I am running a string radius profile so all the pole pieces are the same distance away from the strings. It's much more balanced - overall - in terms of response. It also sounds BIGGER when listening to playbacks from the previous sessions.
There is a "snarl" to this pickup that gives it a kind of mildly compressed, yet very natural sounding effect...the best way I can describe the tone.
A very good fit for this S-G...