I've had a HPG Recon Kit Bag (full size), for about 3 or 4 years now and I wouldn't take anything for it. It's just too handy. I leave fire starting components in there, wet wipes (for the doo-doo), small emergency kit, small led light, my pistol rides in the back portion of it. I'm never in the woods without it anymore.
I like the molle on the front. That's where my old kuiu binocular harness rides.
Like mentioned earlier, it can slip down if you start loading it up too much. That's when it's nice to just dock it to your pack.
When I first got it, I was on the fence about how much I'd actually use it, but like I said, I'm hardly ever without it in the woods.
Looking at the Steelhead, it looks like it is deeper front to back than HPG kit bags. Maybe, maybe not. For me personally, I limit my front side to just the kit bag and sometimes my bino harness. Not knocking anybody else's preference, but I see people strapping more and more garb to their front side and it's getting ridiculous and cumbersome looking to me. I like the looks of Marsupial Gear, but some of that looks like it's getting out of hand with the bino harness, RF pocket, wind checker pocket, etc. piling up on your front side. I don't know. That's just me. The Recon Bag is about right to me in terms of thickness. No issues shooting a bow with it on.
If you haven't seen Kifaru's new video "Kings of the Mountain", I do wonder how much grief Frank gave that kid on there for sporting that HPG Kit Bag.
Damn, that got long.