I just got my vero 4k and did some tests today with a external dvd/bluray burner (made by lg) i borrowed from work and it worked great with all the dics i tested today (of course bd-j menus are not yet supported, but the progress on this looks good with vlc 3.0.0).
I know bluray decryption will probably always be a problem on linux but this is another topic.
The only real problem i had with this setup was that the drive was quite loud with some discs, i dont mind this at the beginning of the movie when the disc is initializing? but with some discs, no matter if dvd or bluray, there was some high pitch hissing noise audible throughout the playback.
Now i was wondering if anyone can recommend a silent extern usb drive without such problems. Doesnt have to be a fast drive or rw capabilities.
If anyone is intrested in the setup:
I have my vero 4k behind my tv near the Input ports and used a Y-USB cable and connected the data port to the vero and the other lead into one of the tvs usb ports. After installing libaccs and libdbplus and downloading a recent aacs key db, i just restarted kodi and it worked out of the box.