Looking for statistics on IPtable best pratices - appears that a server like www.cloudflare.com would parse iptables and look for gaps and trends in iptable configs - but don't think they'd publish their findings. FYI: I just heard about cloudflare, haven't used it, and have nothing to do with them. If you're aware of other services like cloudflare, please post links.
one thing to keep in mind - 32bit counters nowadays tend to be not enough. if you count bytes they might flip over in less than monitoring interval [eg 5 min]. so remember to store and read data as 64bit integers.