A custom kernel can improve your battery life tremendously (I swear by Incredikernel, but there are other great kernels out there as well. Since your on CM7 just be sure you use an AOSP kernel and not a Sense kernel). The MIUI camera is superior to the stock camera that comes with CM7, it takes better pictures and has more options (though to be fair, the CM7 camera has made some improvements lately). As for the radio, unless you have to update/change your radio for some reason I would recommend that you don't mess with it.
I flashed radios to be "part of the cool crowd", but I will say this. There are areas where I live that have dead zones. Everyone has them. But with 11.19 radio, the places I had no signal I now have at least 1 bar, and although the signal bar really isn't the best way to judge signal, I can make/receive calls and use data in these same areas, so it was worth it to flash a new radio, for me anyway.
But as usual, DWM is correct. You can very easily turn your Inc into a paper weight.