Upgrading is completely optional, so it is up to you to decide if it is worth it to you to purchase an upgrade. With each new version of our software we do try to make it more flexible, easier to use and more robust (eliminate known bugs and otherwise improve performance). You can review the What's New information for the applicable software by going to the Information page for that software (Under Software Shortcuts, click on the Information link, then click on the software product and go to the What's New tab). That will show you the changes in the newest version of the software. You can click on the link near the bottom of that page to drill back to the previous version's changes. You can drill back as far as you wish.
Note: Upgrade pricing is only available to those upgrading from a supported version of the software. We only support the last 5 years of versions for each software product that we offer. If your version is no longer available on our downloads page, then it is no longer supported. If your version is no longer supported, you would need to purchase a new license to get the latest version of the software.