Sure hope so - that's almost exactly the same dimensions as the room I'm building out now. I'm far from an expert on this, but I've been doing an awful lot of reading on the subject, so I have thoughts on the matter, but please don't base any big decisions on anything I say.
I think in general - when tracking in a room this small, it's better to just try to remove the room as much as possible. You're just not going to get any natural sort of reverb or decent "room sound". Make the room as dead as possible and add the reverb in the box later. No reason it shouldn't be fine for mixing as long as the room is properly treated.
I just carried down four bags of Roxul Safe n' Sound into my little bitty room. I think I can get four floor-to-ceiling superchunk-style bass traps and still have enough left over to stuff the ceiling joists. Then I'll cover the ceiling with muslin and that should take the ceiling entirely out of the equation. I've got 8 panels to hang on the walls, all 4' x 2', four are 4" thick, 4 are 2" thick. They're some kind of fiberglass substance - it's the same stuff my local indoor gun range uses between the lanes.
I think even Ethan Winer would say that should be enough.