[JoeD]

As a reader I vote no DRM. Mainly because it means readers don't need to spend time removing it to ensure continued access to the book long term as the standard format devices support changes or the best hardware changes.

DRM won't stop piracy in any way, so we can exclude that as a reason for using it. The only real reason I can think of is to stop "casual" copying by non-technically minded people. By that I mean, the equivalent of lending your paper book to a friend.

I don't see that as a major issue either, since it'd be small scale and more likely to introduce new readers to your books. Chances are they'll buy your newer releases when they see them on Amazon rather than expect their friend to keep buying them and passing them a copy (if they don't their friend may eventually decide they're being taken advantage of and stop "lending" them books). A benefit of more readers even if some read a copy from a friend, is an increased chance of discussion about your book online, which in turn means it's more likely a non-fan will see the discussion and consider reading that book in the future.

In addition, whilst DRM is still common, you can get a small PR gain by not using it. People will point out DRM free books when they can and often buy them just to support an author who's taking a stand. Not guaranteed by any means and eventually if everyone goes DRM free the PR benefit will be gone, but food for thought until then.

It's worth noting that whilst most people will not know about DRM and will buy it anyway, you can lose some sales to people who do know what DRM is and/or have been burned by it at some stage. Since a book even with DRM will be pirated, it seems illogical to me to cut out any potential sales by including it. Those who bought it with DRM will still buy it without DRM (since they're not even aware of it), those who refused to on the principle of DRM may now buy it when before they wouldn't. Finally, those who pirated it when it had DRM will still pirate it without.