The stock ROM is great but it's the tweaks and mods that make custom ROM's better, battery percent mods, tablet UI, notification toggles, lock screen targets etc. I too am not interested in over clocking the N7, it's good enough stock and overclocking is only going to wear out my hardware quicker from the heat.
I'm really liking Paranoid Android and it's customization, it's like no other ROM available with it's hybrid tablet mode. I did try it on my S2 but hybrid tablet mode does not work so well on a smaller screen, it does look great on the N7 though.