i just referred back to your previous posts to see what you had going on. i think what you listed would definitely fit. in the first pic i sent, i had the X-E1 with the 18-55 and two primes, one on either side of it. and i think i had a windbreaker and an apple in the top compartment which you could replace for your longer zoom.
^
currently, i'm using my Hatchback as my lens storage while i'm mostly using my m43 system at this time. so, just to give you an idea: my 16L has four primes in the lower compartment and...
^
the 50-140 in the top compartment. those are just the lenses. i have my X-E2 and X-T1 in another bag.
i say it's a great daypack when you're not all about your gear. have maybe just a couple of primes, spare batteries, a sweater and some snacks & bottled water, and you're good for the streets where you mostly stick to one or two focal lengths (where you don't have to switch lenses often which means having to remove the bag). i'll get to more about this in a moment.
i like the fact that it's a backpack to help divide the weight between both shoulders. i've had slings in the past, but i started to hate the design because (as i believe you, too, have mentioned) they're usually designed for one shoulder. at least with my messenger bags, i could always switch shoulders once one shoulder starts cramping.
so to continue about the 16L, you definitely have to remove the bag to get to the lower, main compartment which faces your backside. even to get to the top compartment, you'll still have to remove the bag. now, if you're traveling and are willing to go to something larger than the Hatchback 16L, then i think that's probably the best thing (especially when traveling) since you'd usually want to fit the most you can in the least amount of bags possible. nobody wants to pay more for more checked luggages. but as far as using it for the streets with a small kit (or even your kit you mentioned), it may be a bit much. at least for me, i rather be more free from such a thing when i'm exploring a town or city doing street photography. that's where i prefer a small messenger bag.
quick access was something i, too, needed to have. of all the Mountain series backpacks from F-stop, my version was the only one with the side-access for quickly one-shouldering the bag underneath my arm and swapping lenses. what's more is that i can do that with both sides of the bag from either shoulder. also, i'm glad this happened to be the smallest Mountain series backpack in the line. i don't think i'd like to go bigger than this (again) even for traveling.
^
here's how easy it is to grab a prime from one side while the bag hangs from one shoulder.
^
i can grab my zoom from the other side while the bag hangs from the other shoulder.
^
just as a size comparison to the 16L. it can be a pretty tall bag - i had an extra set of clothes in there.
^
or with less packed in the top compartment, you can roll the top down to make it a shorter bag.
hope that helps.
(Sent from another Galaxy)