Yep - All my Montane and Osprey packs have an adjustable back system. Weigh around 1kg for most 30-44 litres sizes and have survived numerous day and overnight trips. The adjustable back ensures a good and comfortable fit.
These are on offer at Trekkit: https://www.trekitt.co.uk/rucksacks...ane-mens-azote-32-blackcloudburst-grey__41739
I looked at the Azote but in the end plumped for the Deuter Futura pro 36, More expensive but i preferred the fit of the Deuter when I tried the two on .
Deuter Mens Futura Pro 36 Black/Graphite
The Futura Pro is quite possibly the most comprehensive hiking pack available. It features a super breathable Aircomfort backsystem, pivoting shoulder straps, pole/axe/helmet attachment points and much, much more.
www.trekitt.co.uk