Well as a Tier 3 dweller just bought myself an Osprey Talon 11 so that I don't have to lug anything large around on my dreadful local walks for the next n months.
Just an update - used this pack on my local walk on Sunday - out for around 5 to 6 hours and found the bag extremely comfortable - I do like Osprey. The bag held waterproof jacket, trousers, sit mat and gloves in the main compartment with room to stuff a couple of other small things in if needed. The smaller compartment held sandwich (cheese but no pickle = disappointing), and would have held more with ease. The side pockets are quite stretchy and held a 600ml bottle. I carried my phone in the other outside pocket. The belt pockets are quite a reasonable size - one held my small camera, and the other held the handwash and mask with plenty of space to spare. There is also a stretchy bit on the front to stow a jacket, and the usual stow on the go points for poles.
Edited to say - the pack is obviously slim on the back, so accessing the water bottle on the side of the bag was awkward without removing the pack - something which I can do with the larger 26l pack. But I am not very bendy anymore, so others may not suffer with this.
Overall, for local day walks, where you don't need mountain paraphernalia - an excellent bag.