Mission Vandal backpack

I would like to buy a decent rucksack, as I simply don't get on with messenger bags.

The Mission Vandal looks great, but here's the catch. I don't know if I'm going to need that one or the smaller one, or if it's comfortable for more than 5 minutes in a shop.

Does anyone have one in London that they'd be willing to lend me for a few days, so I can road test? I would obviously buy you a few beers and leave something with you of equal value or a deposit and take very good care of it!

I realise it's a long shot as if you have one you probably use it most if not every day, but here's hoping.

Just buy a not so great rucksack of a similar size (for pennies) and if you don't like it you're only down by that amount.

Problem solved. Next!

Not quite, it's not just the size I want to test (insert joke)

I had vandal for few weeks. Was too large for me (im around 67kg and 181cm tall). Its not a backpack, more like large outdoor backpack (or what are they called? Wiki says "technical pack") in my opinion.

Rambler is just enough for books, gym stuff, laptop when not expanded. When I come home from all that and go buy some groceries the expandable area does the trick.