Is it safe to move a copy of your 'themes' folder to a different place in your site's account, whenever a WP upgrade is going on? Since I am on dialup and my connection can be ultra-slow, ftp can take ages. And as everyone knows, the entire contents of the WP site are wiped out every time an ftp upgrade is in effect. It seems the powers-that-be have made upgrading somewhat easier (less painful for those few of us who still have to use a slow connection--thanks whoever you are!!), but this question was one that came to mind recently when I couldn't put off upgrading to 3.2.1 any longer...
I have a few larger (several MB in some cases) themes that I'd rather keep for my own experimental purposes on a test site of mine. And no one likes spending extra time when so many of us don't have a lot of leisure...!
So, would it be OK to just copy out my themes folder, away from the WP folder, next time there's a need to upgrade...or would doing that corrupt my theme files?