Play:5 hardware revisions

I recently purchased a used Sonos speaker from Amazon. It was advertised as a Play:5 but the label on the back says ZonePlayer 5s. It appears to be about 5 years old. Here is what the controller says about it:

PLAY:5: Family Room
Version: 4.2 (build 24071060)
Hardware Version: 1.16.4.1-1
IP Address: 192.168.1.10
OTP: 1.1.1(1-16-4-zp5s-0.5)

So it is running the latest firmware, but I'm curious about the differences in the hardware compared to the latest production models. Am I missing any features? Any other reason why I should exchange this for a newer one? It seems to work normally and sounds just fine.

Also, what does the OTP information mean? It is the only component in my system which this applies to.

Thanks for your advice.