We already know [deflate encoding is a winner](https://stackoverflow.com/questions/388595/why-use-deflate-instead-of-gzip-for-text-files-served-by-apache) over gzip with respect to speed of encoding, decoding and compression size.

So why do no large sites (that I can find) send it (when I use a browser that accepts it)?

[Yahoo claims](http://developer.yahoo.com/performance/rules.html#gzip) deflate is "less effective". Why?

I maintain HTTP server software that prefers deflate, so I'd like to know if there's some really good reason not to continue doing so.