Should I sell my Oppo 205?

With the money gained from the sale, your unlikely to be able to replace it with anything that does anything it does much better, and it won't be able to do the other things .
If this was sold with a different label through boutique stores at double or more the price it still would have garnered great reviews and no one would complain about the current prices.
There's a reason they can still fetch the prices they do, even if they cost much more used than new.
Everyone is entitled to their subjective opinion. Here's and objective one.: 

Review and Measurements of Oppo UDP-205 UHD Player | Audio Science Review (ASR) Forum

While a bit dated, it's still pretty competitive, especially when one considers all else it does.

There is no reason to sell it and you can use it for other formats as well what i have discovered over the years is that when you sell something you usually always regret getting rid of a good or great piece of gear.

Take the money and run. Unless you get a disk spinning habit going.

That's right; take the money and run by selling it to me.

I now used it as a CD/SACD transport to feed in a DAC for two channel music. Because it has USB input, I also play DSD file through it. As a transport it is a great sounding unit. PS Audio comes out their new SACD transport that can do what 205 does for two channel music, and it doesn’t have a streamer. It’s also at considerable higher price.

it’s a bargain at current asking price because it’s a great piece for both audiophiles and videophiles.

keep it!