Here are pics of my 30 filled, no sag at all, but a little pooching inwards betwixt the handles. I have it filled with a pochette full of crap, groom zc, agenda, wapity full of lip stuffs & a bunch of change.
my epi 25 does not sag at all...it retains it's shape really well! the top does fold in a bit tho because i'm a bit careless when throwing in my stuff or taking out something big like my wallet.