We were there this weekend (Thurs-Sun) and I checked out the ears. They were $25 and definitely felt "bulky" because of the battery area. We didn't buy them and saw very few people with them during WoC. Other than the CMs, I saw maybe 10 in my viewing range. We had the reserved section, so we were in the middle and could see a lot of the standing areas near us. I was hoping to see more in the crowd, so it was disappointing. In the Mad T Party area, I think I saw 4 or 5 people with them out of the hundreds that were there.
The price and bulk definitely stopped me from buying them.