Actually squid is fast enough for us :-) And, as I already pointed out in comments to the post: Before choosing Squid 3.0 I've discussed this with percona guys

Actually squid is fast enough for us :-) And, as I already pointed out in comments to the post: Before choosing Squid 3.0 I've discussed this with percona guys (which I really trust since I worked there quite a while) and they shared with my some really weird stories from their experience (on boardreader.com) with Varnish (constant memory leaks, crashes, etc). So, I decided to go with Squid and pretty happy about the result so far.