I believe the answer to a particular hardware setup all depends on user requirements specified.
For a small office with a physician on a limited budget that is not interested in playing with a more complicated IT hardware configuration, a NAS is a very workable and lower cost solution. This is how I thought Bill described himself. If Bill can spare the extra change and doesn't mind configuring and maintaining a server, then he may as well take that jump at the outset as Bert suggests. But if his office will not grow, a server may be over engineering the solution.
High availability and high performance decisions are a matter of user requirements and the amount of money you have available against those requirements. A NAS with the proper RAID setup and attached Uninterruptable Power Supply (UPS) is an appropriate level of availability for most offices. It probably is better than most offices have now.
As an office has more physicians and system demands, then an upgrade to a server configuration with attached storage is preferable. A server can provide many more functions than a simple NAS but the configuration complexity goes up as well. This is a natural step on the upgrade path as you become more familiar with the demands of your IT setup.
About 1 year ago I recommended to AC support team that they publish recommended hardware configuration. They didn't want to do this as AC could run on so many different configurations. Maybe it is time to revisit this.
