My experience only - since I live only a few miles from Google's HQ, I have visited with their adsense team periodically over the years. I gotta say, they really don't care if you take their suggestions or not. It's normally just a focus group and the people who run the group normally tend to agree with all of our user frustrations.
Anyway, I think these focus groups and invitations to participate won't harm you whether you participate or not. Just my hpov.