I'm thinking of using LoginRadius social site login/registration solution to integrate with traditional login/registration system. Has anyone ever used it and have any opinion about its performance and know of any other similar products/services?
I do not have an opinion to pass along to you. Neither do I have any comment on performance. Obviously the products/service your looking at is in beta. Also note that some CMS have this built in or have extensions you can add for social login or sso. Here is some more info and providers: