I have used Renaissance for one year and have also used a different supplier and National Grid directly, so I am comparing those experiences. I swapped to Renaissance when my existing contract expired. I was able to lock in a rate of ~$0.13 for a period of 13 months. As I approached the end of my 13 month contract, I emailed them to see what the rates would be because usually it changes to a variable amount and I would switch if it would cost me more. They offered me the option to lock-in for another year at basically the same rate, which is a no brainer as Massachusetts National Grid rates are 2-3x higher. They also told me that there is no cancellation or early termination fee, which is a huge plus, as when I canceled my previous plan early, they charged me $150. So far, I have had no problems with Renaissance and find their rates to be competitive, and their customer service is even better.