I recently installed Fedora 18 using EFI boot. Like the other current linux distributions, it sets up GRUB2 for me.
I have experience with re-installing the BIOS version of GRUB when things go wrong. I know e.g. how to boot a rescue disc, chroot into the installed system, run
grub-install and possibly
How would I reinstall the EFI version of GRUB when things go wrong? (I know things will go wrong: I break them).
efibootmgris sufficient to update the entry in the UEFI menu. I don't know about rEFInd or SHIM. I personally don't chain multiple boot loaders. All operating systems are added to the UEFI boot menu and it's working perfectly fine.