It's pretty good, except my experience is that __parameters works only in the narrow case of a verbatim forward. I rarely find I need to implement a verbatim forward; I almost always seem to encounter a forwarding pattern when it is necessary to perform a parameter transformation of some kind, or a parameter injection. You need to be able to handle the arguments and iterate/manipulate them.

I find I'm typically synthesising wrappers or shim's, not verbatim forwarding... which isn't strictly the topic of this thread, but it's a 100% related problem, and it seems to be what I actually need to do 95% of the time rather than the challenge in the OP.