What I have a major league problem with is asking moms to do so with the express intent of discussing Medela and their products to the exclusion of all others. What I also have a problem with is telling moms exactly where to go and how to get their foots in the door and then telling them to report back to Medela to share where they posted, including the link to any and all discussions that they either started or participated in and exactly what was talked about. I view this as nothing more than a sophisticated new step in helping Medela target communities for spam of their products
But having worked in Marketing, Product Development and Usability Research for a long time, I think it's really valuable to hear first hand about issues your potential customers might have. I once worked for a company that provided information to Librarians. I signed up for a Librarian listserve (this was in the late 90s). They let me on and I mostly lurked. Every once in a while a question about our service would come up and I would wait to answer and I would wait to see what people said about us. I would then, gently come on and say I worked for the company, correct any misconceptions, thank them for their time and invite them to contact me privately. I worked in Prod Development - not actually marketing. So - I don't necessarily view the mavens it as a means to spam, but as a way of keeping in touch with their customers, issues, concerns, etc - ie problems to solve. I don't really see the Internet as a private place - it's all public as far as I'm concerned.
Like - back 5-7 years ago, who knew you needed the Medela horns to be in different sizes? You have to hear a lot about different-shaped breasts and all to know that could be a problem.