Pros: Forces more investment in Renewable Energy
I had a great experience buying RECs through VGE. The site was intuitive and I quickly received a package from them with a decal and a certificate recognizing my contribution.
At least for me, the value proposition of RECs is easier to understand than Carbon Offsets. In states where major utilities are required to purchase some of their power from renewable sources, if enough people purchase the rights to that renewable power away from the utilities, the utilities then have to invest in more renewable sources to maintain their quota. It's seems more directly impacting to me.