The Schrade-Walden tang stamp indicates that your knife was made before 1973.
As far as collecting or using, and value... that's a tough question. Since Schrade went out of business the eBay prices for Old Timer knives has skyrocketed. Unfortunately the 8OT was one of the models available at a huge closeout discount from Smoky Mountain Knife Works and there are many of them available. But the older tang stamp does make the knife more collectible that the "Schrade" Old Timers, and more valuable.
You can do a Completed Items search on eBay to see what other 8OT knives have sold for, and you'll probably see some with the older stamps. I have been watching OldTimer prices on eBay lately; I'm really just guessing, but I'd say an unused 8OT with the Walden tang stamp would be worth around $50.
To use or not to use... Many people carry knives for everyday use that cost much more than your's. So it's more a matter of "replacability" not cost. You will be able to find a replacement 8OT easily, probably any time you want one. But finding one with your specific tang stamp is going to be more difficult.
Personally, here's what I'd do. If the knife has any sentimental value, I'd stash it away for safekeeping. If the knife is in new condition I'd add it to my collection. If the knife is already used and/or in poor condition, I'd keep using it.
Best Wishes,
Bob
