IMO renting a domain is quite risky and I would never do it.
What if you spend thousands of $ and hundreds of hrs time working on the website, promotions, SEO, etc. After a year (assuming a yrly lease) the owner gets a nice offer and sells the name (much higher price than you could have got a for the prior yr if you would have purch it at that time).
Another possibility is the owner does not sell but sees your website is nice and profitable so he raises the rent several hundred percent.
With either case you are going to lose big time. If you switch domains you lose your links, name recognition value, bookmarks, typeins and SE rank, etc.