.... the purpose of Inline::C is to be a more friendly integration between the languages than XS

Well ... Inline::C is, in the final analysis, nothing other than XS. The "friendly" aspect of it is that it automatically does all of the work for you - it automatically creates the entire XS distro (Makefile.PL, XS file, pm file), compiles it, installs it, then executes the script.
I don't think I've ever expected more friendliness than that - but that's not really a benchmark that should be set by me.

I think it's reasonable to ask Inline::C to do a little more work than perl's default typemap.

I think Inline::C already does that by providing us with the TYPEMAPS configuration option - so that, if the default typemap doesn't do what we want, then we can fix that using our own custom typemap.
I guess there's always room for improvement, but Inline::C should also avoid attempts at reading minds.
It's also currently being actively maintained - so feature requests, bug fixes, patches would all be considered.

Cheers,
Rob