This was requested a few years ago, but bears reposting as Studio One attracts more users.
Studio One desperately needs 5.1/7.1 support - interleaved files, track format, mixing, and within AAF/OMF imports. Working in film, TV, games, and even advertising this is a must. We are on 4.5 now, and at least by version 5, Studio One needs surround to retain some of us who work in these sectors of the industry. The workarounds (mono/stereo track bussing) are not viable for proper surround mixing.
Studio One has so many advantages for us over other DAWs, but having to move our mixes out of S1 to mix is not only a hassle, but it limits Studio One's advancement into our market with other users. Add surround - 5.1/7.1 with at least the hooks in place to expand to larger formats, Ambisonics, 360/VR, etc down the road.