I agree with the previous comments. My main reading device is a Sony, and I only buy books from Amazon that I really want and can't get elsewhere. After I've downloaded them to my Kindle 3 it takes me perhaps a minute to load them on to my Sony.
I agree that the 'average street user' neither knows about nor cares about DRM, and doesn't know how to remove it. You're not likely to lose their custom if you put DRM on your ebook, and you're not likely to lose the custom of people who know the magic incantations to remove DRM. But you might lose the custom of people who resent having you or Amazon control what we do with ebooks we have paid for.
I suggest that there is very little if any advantage to you to put DRM on your ebook, and some disadvantage.
Like every one else who has responded I have never sold an ebook from which I have removed the DRM. So there has never been any loss to the author or even to Amazon.