I'm considering trying to get more granular analytics for my sites than the free plan on my current provider, Clicky, provides.
Piwik looks like a strong contender in the analytics space (and I'm surprised I haven't heard about it before) but I want to be sure I'm not throwing the baby out with the bathwater by swapping to it.
Does anyone have any experience with this software and - in particular - are there any people out there who've tried customising the code or developing their own plugin?
To add to ghommey's response: we're also using Piwik right now and it fits the bill for our purposes. Separating IP ranges isn't really a concern for us as we use separate development and deployment servers.
As for customizing it, I've written a couple of Piwik plugins, one of which served to enable SSO for our (non-PHP) project. Writing the code itself has been relatively straightforward; however their authentication cookies violate the HTTP cookie RFCs (RFC2109 and RFC2068) in that they use illegal characters so there might be also other dragons in places.