The concept that the protocol multiplexer uses is pretty sound and simple. I have and would continue to deploy in production, but as usual you have to know what is going on and what the implications are. You do pay a known penalty in complexity and startup time but you gain a world of obscurity. It's like every other tool; it has it's uses, but it's not suitable for all problems.
The fact that an implementation is possible in a few pages of C goes a long way, especially when the install base for that tool is small and you need to understand the details. If nothing else, the concept stands on it's own and might offer ideas in solving other problems.
Here is a better idea. If it looks like a duck, walks like a duck and quacks like a duck, is it a duck? Run ssh on port 443 at the same time you run a web server on the same port. http://www.rutschle.net/tech/sslh.shtml I've seen implementatios in about a page of C, which I can vet.