Care to explain to us how that is the native Windows 7 start menu? How are they going to make it part of the OS if Microsoft took out the Start Menu codes from the registry and the system itself?
Start is back does not require any previous Windows 7 files, and I am not entirely sure how the Win7 code has been taken, but during install it hooks right into Explorer. This also does not kill Metro, as opposed to Ex7ForWin8, which replaced the entire Explorer.exe binary.
Haven't tried SIB myself, used his previous ExForWin7, guessing it's along similar lines. It installs the Windows 7 Explorer as an alternate shell, not a knockoff but the actual files from the Windows 7 ISO, it'll ask for it during the installation. (Installs elsewhere, doesn't overwrite the original, and you'll still retain Win8's file manager.) Couple very minor quirks aside it worked quite well, and would guess SIB improves on it.. very rarely had the desire to switch to the Win7 shell so never bothered to update it.. purely using for easymode start screen organization then switching back.
Start8 isn't a very good imitation either, and looks bad from design point. I'd rather have the real deal.