Search also perlapi for SvIOKp

Yes, Inline::C has always been my first goto, and I've written plenty of XSubs that reference SvIOK and friends.
But this is the first time that I've ever been interested in SvIOKp and friends, and I didn't know about them even though they're mentioned in perlapi.
Thanks for bringing them to my attention.

I had a little play with them in Inline::C last night, shortly after reading your reply, and an XSub that returned

 SvIOK(sv) | SvNOK(sv) | SvIOKp(sv) | SvNOKp() | SvUOK(sv)
[download]

provided me with all that I needed.
The only problem being that Inline::C is not core :-(

Cheers,
Rob