That said, there are some really good ROM's out there, though, like PAC ROM and Paranoid Android. You can pretty much control your battery life and do huge amounts of tweaking. For example I've gotten about a weeks battery life out of my Nexus 7 tablet simply by under clocking the CPU to 800mhz, instead of running it on the 1.3mhz it ships with. Some ROM's aren't too good with battery regardless, true. Such as the Vanir ROM - no matter what I did with the kernel the thing still just drained very quickly. For Nexus devices, unlocked, rooted yet stock is still the best way to go in most cases. If you don't like the launcher well, that's what Nova Launcher is for.