PHP & XML

Let me preface this by saying that I know the benefits of using XML with regards to portability and extensibility. Here is the issue I face. I have all of my data stored in a MySQL database. I'm considering reworking my website so that it uses XML (after being converted from resultant records in my DB) to transmit & XSLT to transform and display the data to my end user. There are a few benifits I can see in sending XML messages as part of the back end processing. However, that seems to be out- weighed by the amount of processing that's going to need to take place in actually serving the data to the user. First I have to query and pull the records from the database. Then, I need to send those records to a function (or functions) to convert it to XML. Then, I need to take that XML data and have PHP use an XSL stylesheet to transform it to HTML before it, finally, gets sent on to the browser. So that's basically 2 conversions that take place on the back end. How much experience have any of you had with doing that? Does it take significantly longer to serve the pages; is there a noticible performance hit? Do you realize more benifit for the back end processes when using XML that makes any additional time it takes to display a page to the user worth it? I'd love to hear about people's experience with this kind of thing so I can better make a decision wrt whether or not I should even go down this route. thnx, Chris