It will remove your current version of DS4 before installing itself... if you're updating from 4.5 to 4.6, your plug-ins will still work fine.  I can't remember off the top of my head if any plug-ins from before then needed updates or not for DS4.

...that said, there are several plug-ins for DS3 that don't work in DS4 (motionmaster, light dome pro are the two that spring to mind), so it would really depend what you currently use.

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