@Chuck: I do not think that "this business model is going to collapse" ;) because of the sponsors (have you seen?) . Let's Encrypt might be just an "add-on" for some big providers. Maybe we'll see a pro version in the future (?). Anyway, like other providers, we are offering Let's Encrypt for free, but we have also Comodo's certificates for all the others requests that L.E. cannot satisfy. (On Plesk Panel the installation on any SSL certificate is very easy, you do not need technical knowledge at all, just have to pay attention to put correct information on the right fields).