consider your height, XL should be ok, I'm only 1 inch taller than you, and it is not over powering me in anyway. Mahina Club have many pix of owners rocking it in different height, check it out if you haven't. As far as how often you will use it, that's on YOUR personal pref, KWIM? I don't carry much, just Damier Medium agenda, panda pochette for my small items, Coach skinny mini, phone, chanel sunny case, may be water or novel depends on occassion. It looks great 'stuffed' or 'smooshy'
, have you try it on IRL?