I've been running McAfee for years now and it has been excellent but I don't like paying for something when I can get the equivalent for free.
So like F-O-R, encouraged by the posts above, I've uninstalled McAfee from one of my laptops and installed MSE. No problems at all. The only thing I would add is that I didn't do the restart to complete the McAfee uninstall but then installed the MSE and let the restart at the end of that clear everything up. Which it did.