I would think so...but I whould admit that I haven't ever kept Rainbowfish of any sort. From what I've been reading though that ratio should be fine...maybe a bit of squabbling between the males but nothing too serious. I'm likely going to be going for a smaller species, Dwarf Neon Rainbowfish as my tank is a bit smaller than yours.
How do you find their schooling? Do they stick close together or scatter around the tank?
ah is always the way with me my boyfriend just brings back random fish and i have to learn about them quick then go pick up the correct number. i asked him to go back for the four young females as i had mostly males and he came back with 3 females and a rosy danio which he thought was one... go figure? anyway before the other females came they have been good as gold really. the biggest male sometime half heartedly chases the others but none move out the way too fast lol. they like to hang in a four at the back when the lights go down seems like they are just chilling. mostly they hang around in pairs in the day. the three youngun think they are danios at the mo as they are that size lol, im hoping as they grow they will join the others. i think its a nice progression from tetras. im getting there i think lol