drupal5.2

I'm currently working on a new site for a non-profit organization. I've installed pathauto module to improve seo (i hope) but since I'm still in the development phase, I've been experimenting with it a bit.

my typical setting would be like this:

[type-name]/[m]/[yy]/[title].html

as you can see, I added the ".html" at the end of the settings so url output will be like this:

cat/10/07/my-pet.html

have you heard any pros and cons about adding that ".html" at the end? would love to hear it. thanks