I want to switch to plex for my TV media center software, I really do but the thing that keeps making me move back to xbmc/kodi is the seek lag (trying to skip to the middle of a movie) and sometimes it just freezes while fast forwarding.
to be fair, I haven't use the plex media center app, my experience is based on chromecast/android app and the android tv app. (my plex server is running a quadcore haswell i5 with 8gb of ram so it should be fairly responsive)
I bought an android TV purely for plex but so far it has been a bit disappointing.