I bought one of these a couple of months ago and I like it - straps are long so no struggle to get it on, although it has leaked slightly after I rode for about an hour in heavy rain.
I go through backpacks quite quickly, usually ones I get off a market for around a tenner. Fed up with this I went out and splurged £70 or so on a Knox - absolute garbage - leaked, zips broke, seams split, all within a couple of months. Went back to market stall stuff until I got the Course pack.
Have you spoken to Knox about it? The rep for them that used to visit us 10 years ago would have been mortified about that performance, unfortunately they may not care as much now?