J - it is irrelevant if you have made your choice.
That being said I literally went in and shot Fuji & Nikon before buying the 70-200. I figure spending that much on a lens wouldn't cost me all that much to completely change platforms. (replacement - selling mine of course) So I tried with mostly open eyes. I say mostly as I wasn't as eager to swap to Nikon as Fuji, but I was surely eager to not own the Canon 70-200. It is FUCKING HUGE. That sucks. That suck is the only suck it has though, the rest is somewhat magic.