I'll chime in as someone who doesnt share a studio but has been asked to. I'm not doing it and don't think I would because
A) I love to blare my tunes while editing yet I don't like wearing headphones
B) I can design/decorate the studio with just my work, my furniture, my tastes
C) My clients won't get confused about whose studio it is or whose work they're looking at or get confused about the branding. I know I got confused the first time I saw Pizza Hut and Taco Bell together in the same space...I was thinking, "Pizza and Tacos??? Somebody's trying to save a dime at the expense of Brand image...just combine the two brands?"
D) some of reasons Dustin mentioned about his studiomate bailing on rent for a couple of months...that concerns me.
E) I live alone...and I prefer my studio be at my loft
Just the other side of the coin for ya