I love that style of a bag, a shame Berghaus doesnt make more of their bag in that style.
If I'd look at this site, you can also see the front of the Rucksack and to me it looks like a rucsack that has a medium to long back, especially when judging the length of the shoulder straps uptill where the Sternum strap attaches
But I am afraid that not many of these packs are being used yet so it will be a hard time finding people who do have experience with these packs, but Berghaus has a + to comfort on my list and for 40 quid I would take the chance if the wallet would allow it and just try this magnificent pack out, might it not work out you can always sell the pack again making only a small dent.
Yours sincerely Ruud