Fives can be used, yes. PLAY:5s gen 1 can not be used, they do not have the 5Ghz antenna necessary to be used as surrounds. 

Better than 2 Ones? Doubtful, unless you’re using them to play a lot of music. There’s just not that much coming from surrounds in movies to notice a big difference, IMHO. Your milage may vary, as you’re asking for an opinion. 

I happen to use a pair of PLAY:1s for both of my Arcs. 

Thanks , it maybe overkill using 2 Fives. I’ll just get 2 Ones instead. Thanks again.

I like FIVE’s for action movies.