You pretty much answered your own question. Gaudy is useful when you're charming mobs you're sorta likely to mischarm on, or can't afford a mischarm (e.g. EM EXP pets, slimes, etc.)
If you *know* you're going to successfully charm the mob (or at least have a pretty good shot), you may as well use Charm+ gear to extend duration. I'll also use charm+ gear with Apollo's Staff on Tough pets so they don't decharm so quickly.
tl;dr: both, situational poop is situational
EDIT:
Bojack said:
I thought Charm+ was like that also...meaning that Charm+ is factored in when your charm hits and then you can take it off...isn't it?
Yep, you can go back to whatever you normally idle/TP in afterward.