Very interesting points here. I've used mod_gzip on Apache for a while, and if you have lots of text documents, it does do a nice job of compressing them. Once your site gets graphical, or you have lots of already compressed files, then it does get less efficient.

You can also have mod_gzip compress output from your CGI scripts too, which is very clever. I've not tested gzip extensivley, but it seems to be reliable, I never had any problems with it.

Interstingly enough if Apache detects that a file is already present in both gzip and raw, then it aborts any inline compression, and sends the existing gzip file automatically. I don't think that the rewrite rule is required, it just happend automatically if you have Multiviews on (I need to check that).

As ever merlyn has a column on inline compression at his site.