Do you want to be able to dual boot on your Galaxy S4? You can finally do so thanks to RomSwitcher mod. Basically, this mod allows you to have a TouchWiz firmware installed, and then you can install an AOSP ROM.
So, if you are bored with your ROM, you can instantly load the other ROM and vice versa. It is pretty stable, and for TouchWiz you can use any kernel where the default one is Perseus kernel and for AOSP you have to use the modified CM kernel.
Installing this mod is very easy and fast. I have personally tried it and haven’t experienced any problems so far.
Download RomSwitcher here
Note: This will work only with the GT-I9500 Galaxy S4 Exynos variant.