One of the cardinal rules when buying a new association management system is to be sure to check references. Presumably the references the vendor provides you are clients of theirs that are happy with the product and services. Of course, it's important to check with references, but one element of reference checking that is often overlooked is longevity of clientele.

What I mean by this is not just checking how many customers a vendor has, but how long they've had their customers. In other words, do they still have customers who have been with them since the company was founded? Or are most of their customers new? Try to find out who their oldest customers are and talk with them. Find out why they've stayed with the company for so long. You'll learn a lot about how the company treats its long-term clients, and you might also learn some "tricks" for dealing with your new vendor.