g1smd - 11:45 pm on Jun 15, 2012 (gmt 0)

If I go completely extensionless, will that cause problems for txt, pdf, etc...also, what about image files? Do I have to remove their extensions in internal links too?

Only HTML pages are accessed with extensionless URLs. URLs for image files and for css and js files still have extensions. All files inside the server will still also have extensions.