I bought the cheap (less than $30) no-name-brand electronic muffs that Harbor Freight sells. I was surprised at how much more comfortable they are, and how much more sound they deaden than a comparable non-electronic set of Silencios I have. I'm a devout plug-and-muff guy, and I found that they really help you hear RO commands through the foam plugs.
At the recent Appleseed shoot, I had a .223 on one side of me, and a .308 on the other. Both other shooters were within three feet of my position. I found shooting with just the muffs fairly uncomfortable; shooting with the muffs and foam plugs was much more enjoyable. Without the electronics turned on, though, it was impossible for me to hear the instructor's commands.