Good afternoon David,
I have two of the 55mm f1.2 Nikkor-S Lenses, both are in the 97xxxx serial number range. One is non-AI and the other is AId. I LOVE THEM!
The Non AI lens was used by me on 30 August 1983 to document the first night landing of the Space shuttle Challenger at Edwards Air Force Base. I was using the Kodak 1000 ASA color negative film. It was the only lens and film combination that would give enough shutter speed to get a usable image as the craft came past me. All the spotlights were pointing at the rear of the craft and none on the sides or nose of the craft.
My second lens I used this summer for a musical "Sing it again Sam" about Sam Cook the singer. I used Kodak 400 ASA chromagenic B&W film from behind the curtains and in the wings. Lighting was many times only a dramatic single spot. Images were perfect. I also used my 50mm f2 Leitz Summicron with a M-6 and for fun tried some shots with my old Contax rangefinder and Sonnar f1.5 All images looked good, BUT I had more usable images from the Nikkor 55mm f1.2
Yes, wide open they have a distinctive look and shallow depth of field, BUT by gosh when you are in need of every bit of shutter speed to stop the subject movement or quell camera shake or get the quality from a slower ASA emulsion, these lenses WILL come through. I love mine for photographing friends at home or parties or at the pub, mounted on either a FM or Nikkormat with a soft release on the shutter button.
David, I would like to try the newer 50mm f1.2 Noct lens, I understand that they will produce a better? image, but the opportunity to use one has never presented itself, So I don't know. I have used the Leitz F1.0 and it looked very good, but I only could use it for a few shots which was not much of a test, again I don't know. I've used the Leitz Summarit f1.5 extensively for 30+ years and the Nikkor 55 f1.2 is superior with the examples I own.
I agree that 200+ GBP is too much to pay. I'd keep my eye on them and not give up on getting one. A very useful piece of glass when you need the speed. I wish you were geographically closer as I'd let you have a play with it, I'm sure you would be impressed. Its no better than anything else when stopped down, but when you need the speed its there.
Hope this helps,
Sam