Questions about the F-Stop ICUs

Trying to do a bunch of research on the F-Stop Loka and had a couple questions about the ICUs:

1) Although Large sizes fit, they basically recommend small/medium (and shallow..). Am I looking at measurements wrong or does this basically make the camera capacity much smaller than my Flipside 300's camera compartment? It's about 12in long x 9.5in wide, plus a little zippered pouch up top.

2) Since the shallow doesn't take up the full depth of the bag, doesn't the bag end up feeling a bit "weird" since it's not full? Does it compress in some way? Given that it creates a BIT (not sure how much?) of a gap between the ICU and the back of the bag, what exactly do people tend to use this storage space for? It's surely not easy to get something out of...?

I use a large sloped ICU in my Loka and it held my 24-105, 16-35 f2.8 II, 70-200 f2.8 II, 50 f1.2, 5d mkII, 580exII, 1.4TC in the ICU. On top of the ICU I had my Lee filters set and bose headphones. I'm not sure what the flipside can hold. I don't have a shallow, but it looks fine with the sloped.

It doesn't feel weird, no. It can compress using the compression straps or gatekeepers. I store my laptop in that gap, it fits perfectly. A medium slope ICU will fit more than the gear you've listed in your sig.