It may be helpful if you indicate what version you would be updating from and to. Generally, this is not a problem, and if it is, you should see this stated in the newer version's Release Notes. Off hand, the last time I recall this being a problem was when updating from PGP 8.x. Also, recently, there have been some people here reporting a problem updating to 10.2 from 10.x, but all working correctly if uninstalling PGP and then doing a fresh install of 10.2. It is correct that if you uninstall, you need to decrypt first.