I use them often. Like TGWIF said, it's a tool. If you're not using out of snobbery then you're missing out on some cool things you and your audience could be hearing. It's not cheating, it's just another way to get voicings that are appropriate for the song... especially when your singer needs to take things up (or down) a bit. It's really a way to play in the correct key, with the correct positions, in a different key.... Or it could be used to double a part in a different position.
I use G7th Capos and while they're on the pricey side, they're totally worth it, no intonation issues, no hassle. They just work right every time.