I can believe it, some of my favorite diaper bags were backpack styles.

I've been carrying my Synapse to Upward. It holds everything we need and then some. Rocky usually snags it and carries it around for me.

Inside I have:
12oz. Kleen Kanteen in water bottle pocket
10 drink mix pouches and my iPhone in the forehead pocket
in the main compartment:
mifi with charger
Z's poms and megaphone
Z's and my jackets
7 snack cracker/cookie pouches
3 juice pouches
my storage clipboard
Rocky's Upward coach's manual
comb and leave in conditioner spray bottle

and the lower and two side compartments have nothing in them!
Rocky is 6'0" and not slight in build. Yet the Synapse looks just fine with him toting it, as it does when I tote it. This bag is amazing!