I’ve rented for a few reasons.
First, I want to make sure the reviews I read about equipment match up to my expectations. Reviews like the ones here at DigiCamReview.com are priceless. I would never consider buying equipment before checking it’s reviews first. But there’s a lot to be said for having equipment in your hands. Does that giant zoom lens make you feel extra conspicuous? Does Image Stabilization (Vibration Reduction if you’re a Nikon) make that much of a difference? I bought my favorite Lens (Canon’s 100mm f/2.8 IS L Macro) because I rented it first to make sure it was perfect. And it was.
I’ve also rented specialty equipment. I went to Africa this year and I knew my 17-40mm and 18-135mm lenses wouldn’t be enough to get good shots of far away animals. After reading tons of reviews and suggestions I knew the best lens for the trip would be Canon’s 100-400mm zoom lens. It’s the perfect safari lens. But at home in California I do food/product photography and landscapes. That lens would be a $1600 hunk of metal and glass gathering dust in the closet. So I rented it for a month. I spent just $250 USD including shipping and insurance. Pretty sweet deal, huh?