I have a Macbook Pro 8,2 and when booting EFI mode instead of with CSM (BIOS), video is completely unusuable, even text only boot has a totally scrambled screen. I haven't found a work around for this yet, so I'm depending on the CSM.
As for rEFIt, it doesn't necessarily require CSM. It's just adept at finding various bootloaders for linux and Windows and Mac OS and presenting them to the user. Those bootloaders can use EFI mode, or may depend on BIOS which on EFI systems means the use of a CSM to "emulate" BIOS. I found rEFIt to be a little confusing as to what's going on and showed numerous options for booting only two of which would work. So I just restored to Apple's EFI startup disk selection menu using option key at startup.
What I've learned so far is that Apple's startup disk menu (option key @ startup) will produce a hard disk icon labeled "Windows" if the follow three things are true about that hard drive: it contains a hybrid MBR rather than a pure GPT, one of the partitions in the MBR has the boot flag set and it doesn't matter which one as long as it is not the protective MBR entry, the first 440 bytes of the disk (LBA 0) contains bootloader code.
In this case, you get a Windows labeled hard disk icon when using option key at startup and when choosing this option it basically means boot into Grub2. From there you can choose whatever your Grub2 configuration has found which could be one or more Linux and Windows installations on that disk.