"Loose" PTs : Templating Best Practices

System

The client is interested in defining an enterprise standard of classic TPLs or "loose" presentation templates (not really XML, no CDATA issues). I need to come up with a list of pros and cons for each approach. As much as I like XML I think it's a bad fit for presentation templates, especially when I have to embed small pieces of Perl all over the place. On the other hand I like being encouraged to output XHTML and I do like having some kind of offline validation before receiving the "unable to parse template" message.

How many people are going each way? What are the issues you are seeing?

Thanks in advance,

-John