Is there any drawback in using friendly-URLs ?

Hi,

I understand the advantage of friendly URLs for search engines.
I’m wondering if there are also drawbacks in using them.

I can figure out the need to carefully choose the document titles so that the url that were linked from other sites or bookmarked do not change.

Maybe some drawback concerning speed or anything else ?

Thanks.

No drawbacks that I can think of...

I can see one drawback to search engines friendly URLs.

When you alter your site structure because your site increases in complexity, search engine friendly URLs will also change and potentially break the links that were done to the pages of your site from external sites.

I wonder if search engine friendly URLs are really so useful.
After all, search engines are now used to deal with dynamic sites. Isn’t it ?

What about using sitemaps instead ?
Does someone have idea if sitemaps as efficient as friendly URLs ?