want to buy a 550

Hi All,

I'm looking to buy the NTV550, great price now.
it will just be used to play files on a local network, i've no interested in Netflix, youtube or other streaming sites.

Can someonce confirm if it plays the following

Plays MKV, WMV HD, AVI, M2TS files
Plays Dolby TrueHD and DTS-MA from MKV and M2TS files
Plays Subtitles from MKV and M2TS
Supports cover art from files located on a NAS

A lot of people on this forum appear to want to sell their's, what exactly are the issues?

Thanks,