JULES771  Well, let's see.

Upon installation, the ProClick 1.6.6 totally disabled USB overdrive.

Then there was no list of installed items so I had to spend about an hour hunting down the files to trash, (by the way, all usb apps will be disabled until you get rid of the razerpro.kext file)

And finally, the app itself is awful, no options to assign buttons for other apps. no tech support, no response to emails.

I could go on but this is hopefully enough to warn others. The ONLY saving feature is that it's free.  
(Version 1.6.6)