I like the idea, but you have to pretty sure you know exactly who your customers are don't you? I would move on if I wasn't on the list. Features are more universal, which I guess is why they are also less effective.
I like how Foursquare appeal to their customer personas, "merchants", "brands", "developers", without making it too obvious but still very findable.
Yes, and that is itself a huge benefit. If going this route forces you to think about who will use your product (hint: it's not "everybody!") then it's a net win for everyone involved. Understanding your customer is key to building a useful product.