The only difference between CentOS and RedHat is the trademarks and logos. They are exactly the same binaries.
I'd add my support to the Live CD/ Live USB stick with one caveat. If you use wireless networking, odds are you're going to run into trouble. A lot of common wireless chipsets (mainly Broadcom) are licensed in such a way that their drivers can't legally be distributed by the distro maintainers. For installation on hardware, that isn't a problem because you can install the drivers after installation. But with a Live CD or USB stick, installing the drivers may be exceedingly difficult or impossible.
Now that said,
UBetbootin is a great way to try out some Linux distros on a USB stick.