I worked at Apple Retail during the Snow Leopard launch. I think I still have a boxed disk somewhere, too. I remember it was not a product I had to sell to customers. People came in asking for it.
Another highlight of that job was selling a green iPod Nano to "John Locke" from LOST
Interesting that you think that of 7.5.3 — it worked, sure, but it could be painfully slow. System 6 was preferable as an OS — MultiFinder was better than 7, at least in the first couple iterations — but much of the software I needed demanded 7. 7.6.x was the first bright spot since 7.1 fixed much of what went wrong in 7.0, & there was a ton of waiting after that. 9 just chugged along for me, for the most part, which was nice.
Loved Snow Leopard too, & was shocked by how bad Lion was in comparison. Glad they got back on track after that.
You were right I forgot about 7.6.1. I think I had a an WiredInc mpeg video card server based on System 7.5.3 for a project. So it had a particular memory burn. I suppose I need up using System 9 since all life forms were supported by carbon.
I still have some 10.6.8 install media for both server and client. Truly loved them both.