Edited (again) :
The two I ordered don’t have a (much) different output impedance. Be sure to measure the impedance before you install them and after. When the braided wiring is badly soldered to the pot (ground) this can add a considerable amount of resistance.
Even though they’re both Classic+ 57, when they become slightly warmer due to outside temperature or just resting on your lap, the output impedance can go down considerably. This means that it can go under the mandatory minimum of 8 kOhms, to what you would expect of a regularly wound Classic Vintage. It can go down ±1kOhm.
Original review :
I installed it on neck and bridge : it’s like the classic vintage ’57 that was accidentally slightly overwound.
The more windings you get, as long as the power goes up, it picks up more overtones and undertones. Take down the output volume on your guitar or clean volume on your amp and you get a really highly defined sound.
They also produce more raw power than the classic vintage. When you allow it to overdrive your amp, it does it well.
Pointers:
To solder new pickups into your guitar, you need a soldering iron of no less than 45 Watts so it heats up properly. 30 Watts won’t cut it. Preferably you should get one with variable temperature to reheat the old solder to make use of it or remove it with desoldering ribbon or a desoldering tip.
Great pickups.