Just to clarify, I don't have a pair of Slash's XX Grade jeans yet. Still working on that, and if I ever do I'll be sure to share them.
I've been wearing my pair of Slash S01XX jeans that I found on Yahoo for the last week, to me they feel very unique even in the limited production one man brand space.
There's something about the way he folds the fabric where different parts of the pattern overlap, it gives them a very three dimensional feeling that can't fully be portrayed through pictures. He's mentioned this on his blog in the past and I never understood it until I started wearing my pair. The only makers that I've seen do something similar are Roy and rebuilt. And his patterning is very good, the cut feels great in the short time that I've been wearing them. Pockets are usable, rise is ample, they feel like what I'd imagine a pair of vintage jeans should feel like. I think he also spends a lot of time and effort improving the fabric and materials used to make each pair. If you look at some of his work over the years it's gotten much more refined from when he first started.
From his blog it appears that he's been heavily invested in recreating vintage two prong buttons from scratch for the XX Grade line. Literally recreating machinery and button casts so that he can reproduce buttons for the small handful of jeans that he is able to make on his own. That's very dedicated, he's not a brand that can easily push out a few thousand pairs of jeans to justify the r&d costs associated.
Does this make them inherently better than other buttons on the market? I don't know, and Slash believes that the only way to understand the difference is to see them in person.
Is there an aspect of hype / limited availability to his concept? Absolutely, but I also don't think it's the main appeal. I think with almost any and every one man brand in this type of field it's intrinsic to keeping their product line alive and commercially viable.
I'm sure there might some people buying them for this reason alone, he's even blogged about how he doesn't want people to resell his products because of their limited nature (saying that he will ban anyone from purchasing from him again if he's able to track them down via the serial number printed on each pair).
I think he's very dedicated to his craft and he's trying to reproduce jeans in the most accurate way possible and he's cultivated a very dedicated fan base along the way.
I understand that the limited nature of his products will put some people off and that's totally understandable.