When to consider base64 (DATA: URI) images?

Question

What are the factors that should trigger thinking about switching images over to Base64 embedded in CSS?

There seems to be a lot of generic pro/con type things out there

Answer 1

When you can use css-sprites, that's definitely better.

One particular case in which I prefer base64 DATA URI is when we have a small image file which will be used as background with repeat-x or repeat-y. Since repeat doesn't play well with css-sprites, you need to use a single image as a source. In this case, I find that using the base64 version is a better alternative which saves you a request to your web server.