I installed CM a few months ago and AC began to stutter, so I hastily uninstalled it. However, it looked so useful that I tried it again last month and it has since worked flawlessly, apart from a problem with showrooms. There are lots of useful functions, such as loading the correct shifter/paddle option for a car. My favourite feature so far is saving grids of cars from the same era, class or power/weight ratio, which ensures close and interesting races. Now that CM is running smoothly, I want to install Sol as soon as the next Sol upgrade appears.
CM is daunting at first (so many options to choose from!) but it is definitely worth installing.