Making the SSH work with C# is indeed very tricky and most of the implementations are either buggy or too slow. When we were making SmarTTY, we struggled with SharpSSH and SSH.Net a lot, and then finally decided to make our own C# wrapper around libssh2.
Although SmarTTY is not open-source, if you want to use its SSH library in your project, feel free to drop me an email. If there's a great demand for a library like that, we might release it as a separate product.
