I think the fanny/lumbar pack is a nearly ideal format for a PSK. I do have a sling pack that I really want to love; it's a great bag with great organization, well made, etc. But it just doesn't carry that well for more technical hikes. It's ideal for a bag to have a vehicle to keep your stuff organized and that could be carried if need be...but it just isn't ideal for steep terrain or rough, rocky ground.

My newest "lumbar" pack is a Mystery Ranch Hot Shot pack. I got it used and pretty filthy but in great condition otherwise. I took it to a car wash and power washed it out, then let it dry in front of a fan. So far I'm very impressed! It has a real frame and a great belt and is supposed to be capable of carrying 70 lbs (although it's only about 1200 ci so no way you'd ever get that in the pack). After a couple of test hikes I may move the contents of my sling pack into the Mystery Ranch fire pack.

Agree with the carry well comment.

Often looked at the Seal Line's Seal Pak Hip Pack, but the simple webbing belt put me off.

My mountiansmith pack has short straps on the bottom to hold a jacket.

Agreed that a fanny pack is just about right for a separate emergency kit. Big enough not to compromise on necessities, but small enough that it's easy to have with you even when you're away from your main bag.

Although they're absurdly expensive, I've been looking into a small chest pack (HPG Snubby) to carry a firearm without interfering with the waist belt on the pack, and while in the hammock, but one version has a second compartment that seems like it would be useful for essentials without getting awkwardly chunky.

I dunno if it has a fanny pack mode where it can be attached to your belt or around your waist with it's own strap as an alternative to chest carry, but it would be nice to have that flexibility.

The HPG Kit Bag works great! I prefer to keep my gun, mags and flashlight in there and very little other stuff; it tends to get unwieldy pretty quick if you overstuff it. A small waist pack for a bit of gear and the Kit Bag is a great combo for day hikes.