You are so right. It really is about the proportions. Not just of the bag tho. For the first time in my life I thought "does this bag make my butt look big(ger)". And yes, yes it does.
hee hee, then you have your answer! I think because it is truly a shrunken down version of the GP 36, it throws things off. IMO, the GP is supposed to be a tote bag, so to me, on me, the 30 never looks quite right.