Thanks .. yes that was me with the tracking/play room and the control room with the green paint.
Regarding the other guy's booth, I'm not really sure. I didn't look closely at what he had for treatment in there at first, but now I see that it looks as though it's covered with foam. Maybe the walls are lined with rigid fiberglass too or something.
I'm not really sure why you wouldn't be able to get a good sound from a room that size. I've seen lots of studios with vocal booths around that size before, including the one at Stax Studios in Atlanta when I took a tour there a few years ago. I wasn't aware that people were saying that a room that size is problematic for vocals.
Edit: Just as with gear, lots of people have opinions on acoustics. Sure, there is a science to it, but if you ever watch documentaries of albums being made, you'll usually find all kinds of examples of a band/artist doing something that someone here would tell you that you can't (or shouldn't) do, yet it doesn't stop them from making an album that goes platinum, etc.