Things like Tamir.SharpSSH.java.String give me the creeps. They wrap and implicitly convert into C# classes, with no real added value. Also, need to look to re-factor out all of the crappy wrappers for IO streams.
Minor comment on the probable reasoning behind these Java wrapper classes, as it's not clear that you see any rationale for using them: I imagine the original author wanted to keep the whole library as close to its Java roots as possible, so that enhancements and bugfixes could be painlessly brought in to the C# version. By isolating .Net-to-Java differences in wrapper classes, the whole thing might have remained much more maintainable with regards to its JSch roots.
That said, given that Jsch went on to be more-or-less consistently maintained for the next 5 years, and SharpSsh was abandoned, I can see how that goal might no longer be realistic anyway.
I'd be inclined to agree with you, particularly as I don't do much maintenance on the library at this point. I no longer use it at work, and my initial modifications were solely geared to that use-case.