My recent computer purchase came with PhD3. I own PhD6. Is there any reason I should keep the legacy program of PhD3?

Sometimes the next generation of software has bugs, maybe its slower or something unintentionally goofy like that -- giving you a reason to keep it. But PhD3 is from so many generations ago, and has so many improvements, I can't see a reason to keep it. I'm about to uninstall but thought I'd ask before making it permanent.

Thanks in advance!