The ability to disable this will be much appreciated. It would be easier on the server, but probably much more difficult to program. Just generate both types of pages, and include whichever the user prefers. I have worked a lot with both databases, and prefer MySQL over PostgreSQL for web development, based on the fact that it is an order of magnitude faster than PostgreSQL and because it natively supports BLOB and large TEXT types, meaning you can use them with the standard API, and because you don't have to figure out how to implement them as user defined types. Seriously speaking, in databases, performance is not necessarily the most important quality.
Data integrity is far more important, and that is where PostgreSQL wins hands down.
Transaction support in PostgreSQL is full-featured and very heavily used by our site. At a certain point MySQL just keels over and dies, while PostgreSQL keeps plugging away. In any case, we are using PostgreSQL, and even with how much traffic we get, we still have a low load on our meager Pentium 200. A lot of the places where people run into trouble with dynamic web pages is using totally dynamic architecture when they don't need it. Much of our site is statically generated pages by regular cron jobs.