I jumped at it.
I have virtually no sales through other outlets. I'm already 99% "exclusive" to Amazon for reasons that I do not know. I haven't sold a single book through Smashwords in the last year, while I've sold several thousand through Amazon. B&N: A handful. Kobo, Sony, Diesel: A handful at best. Apple iStore: Well, 1 that I know of.
Amazon and Smashwords are the only outlets that let me sell my book without DRM. Thanks to that, anyone who wants an epub version would actually do better ordering from Amazon and converting to epub with Calibre than ordering through B&N and getting a DRM-crippled version!
I'm not expecting a lot of income from KDP Select. Amazon's example assumes that your book accounts for 1.5% of all "borrows!" And in my case, how many people are going to use up their monthly "borrow" to save $2.99 when they could save three or four times that much on a more expensive, mainstream book?
But, I have virtually nothing to lose by going exclusively with Amazon for three months. If I weren't someone who was willing to roll the dice, I wouldn't be an indie publisher!