Quote Originally Posted by peety3 View Post
Borrow, rent or steal, ok, borrow or rent the lens you want and see for yourself. Visit a camera store and try one in-store. By all means, don't buy a lens just because a bunch of folks on a forum told you that it's the right choice, as it's your money on the line.
Yes, it's your money on the line. But if you have some trust in the good folks of a forum (such as this one), the collective advice of people can be an important data point for a decision. On a larger scale, this is part of amazon's secret - lots of user reviews that build trust.

Renting a lens before buying is obviously a great idea (and probably worth it for very expensive lenses). But for a $600 lens, as a percentage of the cost, it's quite expensive.For the same money, you can (and I have) buy the lens, use it for a month, and resell it on amazon as "used-like new" if you don't want it (especially with L lenses). I did this with the sigma 8-16mm, which I used for a trip and then resold for a "loss" that was less than the cost of renting for a week.