With integrated pipeline, all requests are passed through ASP.NET, including images, CSS.
Whereas, in classic pipeline, only requests for ASPX pages are by default passe
I'd say you're right, but I' look at it from another perspective.
Do you need to process the requests for the non-ASPX pages ? For example, to log them, or to forbid the response if some condition is not met.
If you need this processing capability, use integrated pipeline. If you don't, use the classic pipeline.