In reply to CurlyStevo:
I've not got a Zenith, but I do have a Zephyr, which is the same bag with a removable lid.
The bag came with a removable alloy stave, which I never use. If I was buying a new one I'd ask them to leave it out.
They're pretty big bags, think POD Black Ice size. Too big for single day winter routes in my opinion. I've also got a Stratos, which is a fair bit bigger than the 37 litre capacity suggests. A good contender for one sack to rule them all.
Aiguille are normally fairly happy to customize their bags to some extent. However don't bother emailing them, they don't do email very well. Give them a call and ask to speak to Adrian, he's a top bloke and knows a lot about climbing and rucksacks.
Re: back lengths I'm 180cm and have a standard back length. Ask Adrian, he'll know what size is best for you.
My Dad has a Triolet. It is a fair bit smaller than a Zephyr/Zenith, much similar in size to a Stratos. It's a nice bag but more complicated and expensive I probably wouldn't bother.
HTH