My wife is going to give me such the stink eye when I start measuring the room the next time we are there.I've always heard that the CBR rooms were 340 and all the other Moderates were 314, pretty much because the CBR was the first non-Deluxe resort Disney built, and thus the rooms were made a bit larger. Then future resorts had smaller rooms. Same went for OKW, the original DVC resort. OKW units are huge compared to the DVC's that followed.
And having stayed in both CBR and POR multiple times, I'd guess most of the added square-footage is in the width of the room, not the depth.
-Rob