I tried the S&K mount on one of my No4's, (mainly for load development)
If set up correctly is solid and holds zero - the positive.
Has little latitude for setting up scope with correct eye relief, even with a older weaver that has the turrets "set forward" - basically scope sits too far back and risks giving the shooter the proverbial "Weatherby eyebrow". Also sets scope a little to high for my liking - the negatives.
Moved onto a Fulton mount later, when i put together my L42 style No4 .7.62 conversion - (whilst i wait for decent quality bracket and pads) a vastly superior no drill mount to the S&K in my opinion
Have also got a Armalon mount, which seems to me to be copy of the Fulton mount (use it for accuracy testing when working on my various No4 projects) again i would consider it to be superior mount to the S&K