mostly i use the motif es on gigs with bands, the PA800 i use much less, only when i have some ethnic style gigs and/or with a singer alone.
sometimes when im not lazy i take both 
the PA800 has great accordion and some ethnic samples,synths also ok, but i don’t like the pianos there and the keyboard feel. i keep it cuz sometimes it get me good money for that kind of gigs i do with it 
i dont know about the PA900…