From right, Nike Grand Pooh-Bah, Scott Overock and a pair of older Sidis
Let's chat a little about vintage mountain bike shoes, these are the current examples in my collection. I din't consider myself a vintage shoe collector, they are all about my size and can be worn and ridden.
The Nike Grand Pooh-Bah was the shoe of choice for John Tomac, which made it the hottest thing going. The sole on these is absolutely crazy stiff and prone to cracking and the toe box is notoriously narrow. Of note though they are a race shoe, they retain the ankle protection.
I assume that this grey pair is the older of the two as it does not have the ACG branding. Note the differences in the lace eyelet styles.
These Scott's are built much more like a touring shoe with a relaxed and very flat sole, and plenty of flex for hike-a-bike sections. I dig the lace covers, which bring to mind old vert skate shoes from Airwalk.
While the others are just more for vintage mtb outings, these Sidi's are my current favorite shoe to ride in. They don't have velcro to loosen like the Sidi Dominators, are stiff, and nothing forms to the foot like Sidi leather. I'm guessing these are from the early 2000's.