The older your system is, the more advantages you will gain from the technology of the new software solution alone. Add to that the improvements in functionality and usability, and an upgrade can revolutionize the way you run your business. And remember, upgrades are our bread and butter. Questions and concerns you have, quite a few other companies have had as well.
It is time when the new version offers significantly more advantages compared to the existing solution, you are working with a very outdated version and your version is no longer updatable.