I just thought that I would put this up for people to see. I have 8 singles (Rev 2 and 3) and chose to include the power adapters because I didn't have a PSU to use them with.
Long story short, out of 8, 1 made a horrendous burning smell when powered on, and 1 died within a week. So that is a 25% failure rate from my experience.
I get that they are cheap, I wasn't expecting much in the way of efficiency, but goodness...for $600, I was hoping that the power adapters would last.
To their credit, BFL has been making an effort to improve CS and I had one replacement in my hands 3 days after I received my singles and discovered the defective adapter. However, when the second one failed, I sent them another email, offering to ship back the defective ones for proof that I wasn't just taking them for a ride. Still haven't heard back after ~2 weeks.
Just an FYI