Yikes! The waterfield sleevecase is starting to grow on me because it's certainly slimmer than the brain cell... it also seems like it'd look better when carried alone. For a similar configuration as the Tom Bihn (vertical, flap, d-rings), it's $69 shipped (vs $68 shipped for the brain cell).
Now for fitting inside my backpack,
North Face Hot Shot SE dimensions: 20.5 in. x 13 in. x 8 in
Tom Bihn Brain Cell dimensions (4Z): 16.6 × 10.4 × 2.3 inches
Waterfield Sleevecase dimensions: 15.35 x 10.8 x 1.95 inches
It seems like it's down to Tom Bihn vs. Waterfield, and both sides have rave reviews. I think the only difference is the amount of padding/protection I'm looking for. I've always been worried about the Macbook Pro's aluminum getting dented up.. Would the sleevecase be adequate considering I'm a college student who bikes to class? I'm not really rough with my stuff, but I do load up my backpack w/ textbooks and I toss around my bags sometimes...