Is using Mendeley to organize my files a good idea?
I've personally used this feature, and I really like it - though honestly, part of the value I get from Mendeley is that I stop worrying about my files and folders and just use the software itself most of the time. As I have it sync them up I'm not even really concerned with where it stores them any more.

My recommendation is just to copy-paste your directory of files to a separate area "just in case", then fire away. File naming is (was) a pet peeve of mine, and I really like to have the files nicely named so I can search them - then I usually also sync that folder to Google Drive so I can access my documents anywhere (phone, guest account, etc).

It's a useful and nice feature, but honestly I found less value from it than I expected precisely as I began using Mendeley more. I still use the feature, but the other things the program does make it almost redundant - but still nice and I'm glad its there.