Seeking multipart-form advise

[Gary VanMatre]

We are working on an application that has several pages that require
file upload capabilities.  Currently, our main tiles layout contains our
html form tag and we are considering adding the
enctype="multipart/form-data" attribute to the form tag in our main
layout but we are uncertain as to the overhead/cost of doing this.  
 
Is there a significant cost associated with making all forms multipart
in your web application?  Any experiences or insights would be greatly
appreciated.
 
Gary