(cross-posted on the main PW page, as well as similar version on the other product pages)
Thanks for your question, it is one that comes up often. The top reasons to go to the cloud are very straight forward. Some have specifically to do with PracticeWorks and some have to do with security.
There are a few reasons you might want to not consider moving to the Cloud:
I hope this helps. Please let us know if you have any questions. Good luck with your decision.