My only concern is change fatigue from faculty, something I would very much like to avoid. As such, we have waited for new quizzes and would like to wait as long as possible before moving. When we move, I think there are two things to help with that:
Very clear and helpful resources to help us help faculty. This can be webinars, documents like the feature comparison chart, and instructions (written and video) on how to use, transfer, etc.
As much time as possible to transition to the new quizzes. Don't force us to transition until there has been at least two semesters since the tool is as close to fully developed as possible.