Hi jayne, Ireplaced my old rucksack earlier last year. I had been using a Berghaus freeflow 35+8 for about 10 yrs, and it was starting to look very tatty.
It took me ages to decide on one, and I eventually settled for the Osprey Kestrel 38l. It doesn't have a freeflow back as such, it has what Osprey call an air escape back panel.
The pack sits snug to my back and has an adjustable setting so you can set the pack correctly to the length of your back.
If your OH uses a "hydration system" when he's out, the Osprey Kestrel has a special pouch and loops to keep it all tidy and out the way.
It has a loop to take an ice axe, and loops to accommodate trekking poles.
IMO I think you would struggle to get a better quality rucksack for the money. I paid just over £100 for mine, and if it serves me as well as my Berghaus i'll be delighted.
When you go to look at, or buy a rucksack you like, spend as much time as you like filling it with pieces of equipment that any good quality outdoor shop should be able to provide you with, in order for your husband to get a proper feel for the pack.
Good luck