Not sure if you picked up the lens already but here's my two cents worth.
When I was using Canon (switched to the dark side about 4 years ago) I had the 70-200 f4 non-IS version for about 3 years.
It was sharp. It was durable. It focused fast. And also mentioned by the previous post - it's MUCH lighter than the IS version - which does help handholding the sucker.
I never had a problem with water/dust/fungus with the lens - and I shot with it in the snow (whistler) and the desert (well.. Vegas...) Those L lenses are built to last.
And speaking of lasting.. don't worry about the age of the lens. I've bought almost all my lenses used and if it's a good one.. it'll continue being a good one for a long while.
Of all my Canon equipment that I've sold when I made my switch - it was the white F4 that I missed the most.
Good luck with your new lens. You'll love it.