I've been back and forth on the Sabre 45. I got one and decided it wasn't for me, sold it, then later decided it was for me and got another. So currently it's my main pack.
Advantages:
- very robust
- OD colour
- comfortable for me (I'm 5'6")
- removable pockets
- big top pocket, holds my waterproofs
Disadvantages:
- narrows at the top - can make loading tricky for larger items - like the dry bag with my sleep system
- with pockets it's very wide
- it's not very tall, so won't fit longer objects like my Sven saw internally (my older pack did)
- not as many external attachment points as some other bags
- NOT a lightweight pack
It's a good pack, but it's not magic, and won't be right for everyone. Your best bet is to try one out in a shop, and see if it suits you. It's a popular pack, so If you get one and decide it's not for you, you can probably sell it here, but obviously at some loss.