On a recent short trip, I one-bagged with my trusty Aeronaut but because I had a few hikes planned, I tossed a no-brand packable day pack in the pocket and wore that for most of my trip. 5 days later, I was in bits. I wasn't carrying around that much each day (water, snacks, jacket, camera, iPad, etc) but because the day pack was just this form sitting on my lower back for most of the day, it wasn't doing me any favours.
So for my next trip, I want to one-bag it again, but have a much more comfortable backpack with me, as I'll be doing a LOT of hiking. Because I'll be flying on an Aer Lingus "regional" flight where they really clamp down on hand luggage, my choices are limited to what I can squeeze into the bottom of an Aeronaut and still have room for a week's worth of clothes. My Brain Bag would be ideal, but it just doesn't tamp down very well and I don't like the idea of folding or rolling it, even if I could.
I'm therefore in the market I think for a comfortable EDC that packs nice and flat, but can still hold everything I need for a multi-hour hike. I'm thinking an S25 (or 19) or a Smart Alec - I believe the multi-hour part means I should get something with straps and whatnot rather than an PCBP. There's plenty of threads on here about the benefits of one over the other, but I'm wondering if anybody has any insights in to how they squash down in the bottom of an Aeronaut.