I skipped the DRM on mine, mostly because of what others have said. It doesn't deter piracy, and the only ones it inhibits are customers who have paid for it. Plus, honestly, I don't mind if someone passes along a copy of my book to a friend. If the friend likes it, they'll buy more of my stuff anyways, so I'll take that one time hit. If they're not going to buy it, they're generally not going to buy it, so I don't lose any sleep either way. It's not like I was going to get their money anyways.