Timbuk2 d-lux messenger bag- what size for the 13?

I am looking to get one of the d-lux racing stripe messenger bags for my 13 inch air. I really think I would prefer the small size, but timbuk2's website recommends the medium. The laptop size chart makes it look like the 13 will fit the small easily.

Does anyone have any experience with this particular bag in the small/medium sizes with the 13 inch air?

fristuff said:

I got one, a small will fit your 13 inch well I got a small one too.

Click to expand...

thanks, so it's not too tight?

edit- how much room does that leave you in the main storage compartment? As in, if you had to put regular sized paper in there, could you fit 100 sheets?