Well, I haven't really read through the entire post, but I did want to mention a few things. I work for a software company (http://www.mainsequence.net,http://www.pcrecruiter.net) and our product is used for (job) recruiters. Our software is an interface for two different types of database, MS Access and MS SQL. We sell the access license to small offices because after 1 GB of data (sometimes a little less) the database becomes unstable and explodes (but it can be repaired), SQL on the other hand handles in the terrabytes.

Most game communities will never get that large, but consider a text file with 10,000 lines in it. Not Good. MySQL is a little different from MS SQL, but the same theory applies. The SQL Server can be hosted on its own seperate computer (which I hope you would if you ran a server), but the point is, a text file can only handle so much before its simply not going to be capable of huge amounts of data. Plus, the extra security that comes with an SQL server is, I think, more than useful.

But I'm always open to discussion and differences of opinion.