I purchased this a while ago after buying a Nike+ sensor. I have run over 600 miles since and never had a problem with it. I only use it on 1 pair of trainers for months on end before replacing my trainers and therefore moving it to a new pair and it has always stayed attached. Perfect for the job!
I brought the Switcheasy as I use several pairs of running shoes and was fed up with having to relace them everytime I moved from one shoe to another. It was simple enough to fit to the shoe and worked well during several runs.