Rum click and rim shots. If will definitely change the sound and fatten up the drum. The top head has more effect than the bottom head so maybe the owner was tring to save some $$$, those hoops are about 50 a piece.

Extra time to experiment with and didn't want to remove the wood hoop.?

Anton Fig has them on every drum of the set he uses on Letterman. Difference in sound between wood hoops and metal is quite noticable.

Why would you use a wood hoop or why would only use one wood hoop?

I had one of my snares set up that way for a while. The wood hoop fattened up the sound and gave the drum a different character. I did have the wood bottom hoop as well but left it off after experimenting with it since it didn't seem to make much difference in the sound and also made it difficult to get the drum on my snare stand and also into the case I had for it. If I had known this going in I probably wouldn't have bothered to buy the bottom hoop since they aren't cheap...maybe this guy already knew that.

Not a bad deal so far as the hoop itself is worth a good chunk of the asking price.

As mentioned, the hoop is worth half the asking price.

I have an Anton Fig snare and it is a pretty great instrument. I always like playing it.