Humbuckers with good single coil split sounds

Update:
i) I just found that Catswhisker Pickups #5 with in their S-Bucker pickups:
http://www.catswhiskerpickups.co.uk/humbucker.html I’ve ordered one and will do a demo soon.

ii) Dean Zelinsky guitars just announced their SideKick pickup which aims to be a “true single coil”: https://deanzelinsky.com/sidekick-pickup

iii) Rautia Guitars Toast-O-Caster, Single-Bucker and Bar-O-Caster pickups look interesting too:
http://www.rautiaguitars.net/toast-o-caster.html
http://www.rautiaguitars.net/singlebucker.html
http://www.rautiaguitars.net/bar-o-caster.html

iv) I’ve seen some people put two single coils or a sustainer in humbucker slot. Another option might be two put a true single coil (or even a noiseless single coil) and a mini humbucker in a single coil slot:
http://www.tdpri.com/forum/tele-home-depot/413620-4th-july-caster-8.html#post5425950

Recently been interested in changing the neck pickup on my guitar to a humbucker that has a coil tap that doesn’t seem to have such a large drop in volume. There seem to be a few different ways to do this:

1) Seymour Duncan and Dimarzio

Seymour Duncan seem to be have experimenting with this for a while. They had their Stag-Mag which is a humbucker made of two true single coils and The P-Rails which is a single/P-90/humbucker all in one:
http://www.seymourduncan.com/blog/the-tone-garage/how-to-get-more-from-your-humbucker-coil-split/

Dimarzio had their DP157 Multibuckers which where two of their rails pickups in one. While both rails where humbucking, one was designed to sound like a humbucker, the other a single coil. Dimarzio discontinued it, and when I emailed to ask why they said “the parts used for it are no longer available”, I’m not sure why that should be in our technologically advanced age, but maybe its because of a legal dispute or something.

Dimarzio also have the bluesbucker which is an interesting humcancelling, but coil splittable P-90 in a humbucker:
http://www.dimarzio.com/pickups/humbuckers/bluesbucker

2) Mismatched coils

Lindy Fralin have their Unbucker pickup which has two heavily mismatched coils. When its coil split, it then has a higher output coil than a humbucker that is just split in half. It sounds pretty good, the disadvantage is that you don’t have full hum cancelling in humbucker mode:

3) Asymmetric coil tapping

Asymmetric coil tapping, doesn’t split the pickup in half like a coil split, it takes one coil and then a few extra winds from the other coil. The disadvantage here is that you don’t have a true single coil anymore:
http://www.geminipickups.co.uk/coil_taps_31.html

4) Partical coil cancellation

Similar to the above, some people just put a resistor across one of the coils:
http://www.musicradar.com/news/guitars/50-steps-to-better-electric-guitar-tone-528489/39

5) Add extra coils to single coil

Finally, this is an idea I had, how I think it should work though is mismatched coils like the Unbucker so that the coil split has more than half the winds, but also a coil tap of the overwound coil when in humbucking mode so that the coils are matched again and you get a proper humbucking tone and hum cancellation. I think it can still be done with a 4 conductor cable, but the connection points would be different than a standard one. Something like:

-------------------------- Single coil hot
       |    1.5K     |
Coil 1 ------------------- Humbucking hot
       |     4K      |
-------------------------- Single coil ground
Coil 2 |     4K      |
-------------------------- Humbucking ground

How it would work is that when you want a single coil you would connect the extra windings on coil 1 and use the middle point between the coils as ground. For Humbucking you would coil tap coil 1 it had the same number of winds as coil 2 and use the humbucking ground. In this example in humbucker mode you get an 8K true humbucker. In single coil you get 5.5K true single.

I also found out PRS are doing something similar, but I can’t say its exactly the same: