Just confirming that yes, the X and S use the same shock with a different linkage.Another alarm bell went off when I saw that the Amazon listing for this shock says it’s for both NC700X and NC700S. Those two NC models do not spec the same amount of rear suspension travel. Perhaps the linkages are different and the shocks are the same. On the other hand, the shocks could be different, therefore the claim that this same aftermarket shock works with either NC model warrants further investigation.
My $0.02 is that shocks, like most motorcycle accessories, are vastly overpriced because the market will bear it. You could probably take a NOS shock from some 1970s streetbike and put it back there and nobody would notice.
Much like smartphones, shocks are basically commodities with very minimal variations in design. Manufacturers are well aware of the risks of commoditisation (where they then must compete on price alone), so they have historically tried to keep the consumer in the dark and come up with ever-vaguer marketing terms like 'pro link' and 'uni trak'. Unfortunately that makes it very hard to compare shocks against each other, so why not gamble with a cheap shock and see what happens? Name brands are just that - names and brands, until there's specific proof about one shock being superior to another one, it's all just smoke, mirrors, and credit cards.
Watching this thread with interest...