The Sabre 35 is a great bit of kit. You won't regret it, quality item, and the four side pockets can hold some large items with easy access. No need to constantly open the main body. I can put a bushcooker/billy/mug in the one outer, binos/58 bottle in the other,. Wildlife hatchet in the mid-outer pocket and maps in the otherside. First Aid kit/spare socks and other snacks and stuff in lid pocket. The inner main body usually takes a 2L water system, spare clothes, food and god knows whatever else you need, it would easily hold a sleeping bag, tarp and thermarest with room. It's one of those packs that copes well with minimal items and yet somehow fills up with loads of kit too.
I've tried loads of alternatives and always come back to the 35. And Mark at Lakeland will always get my money as you can't beat great customer service.