 <p>MySQL can handle the load, so the question now is how do you want to use the data?</p> <p>If the churches are separate, do not need to interoperate and even prefer to remain completely independent, then the multi-install case may be a good fit.</p> <p>On the other hand, if you want to integrate the data from the churches, then there should be one database.</p> <p>Whenever thinking of doing a database, please think of how you want to use it. So much comes down to data interoperability (or lack thereof).</p>