I got this email this week from Kindle Direct Publishing (KDP) and I wanted to share my opinion on it. I would strongly recommend you apply Digital Rights Management to your books and not allow people to download your manuscript.
It's unfortunate, but a lot of books already get duped (including my own), and allowing people to instantly download your files just because they purchase a low-cost ebook means the easier it is for people to snag your files and duplicate your work.
It's always best to protect these digital assets of ours!