I'm sure every photographer has gone on a bag quest at some point during their career, many probably haven't completed this quest, and I've been at it myself for a while.
I have several backpacks and sling bags, actually, let me count real quick. 4 Backpacks, 4 sling bags, and they all fit their purpose for certain types of jobs our outings. I've always wanted the perfect day bag, something I could carry a small photo kit inside with room to spare for personal items. My current backpack nearly fits the bill, but it's got a few annoying tidbits that I'm getting tired of. Zipper on the top gets stuck, no built in waterproof cover, it opens weird, would like to have more targeted camera gear space, not a whole lot of ways to attach things to the outside of the pack. the tripod strap is secured via velcro?!
That's the bag that I'm currently using, I really enjoy it, but as stated above, the tiny little gripes I have with this thing have kept me searching for the perfect day pack. I got that bag for $40 "used", since then it's been discontinued and now retails for over $100, crazy.
When I checked my email a few days ago, I saw that LowePro had a new bag line coming out, I was immediately intrigued.
Flipside TREK? I still have the original flipside bag, I really like how you access the camera section from the back, and how you don't have to set it down, it's grey, with olive (my favorite colors!) It's got a rain fly inside it, it's got plenty of room for what I'm carrying now with room to spare! Shoulder and waist straps are an added plus. I could see myself using this bag for a majority of my day hikes in the mountains. straps on the back that can be reconfigured, loops to attach more gear, the size looks perfect, and it's got a dedicated tablet sleeve as well. There's nothing about this bag I do not like.
A majority of the bags I own are made by LowePro, they come out with some of the best products when it comes to camera bags. LowePro, It would appear you have designed the bag that I've always wanted, the one I've been searching for, now I'm just waiting for my shipment confirmation.