I use several stats programs – I think awstats has a decent measurement of repeat traffic.
Well, I don’t know whether you will have traffic when you merge the sites – you may want to ask classics about whether you can get away with temporarily just linking the domains to the major site like I did, or maybe pointing them?
I do not want to say anything about this because I am not very knowledgeable and rely on others to counsel me with these things. You better ask someone else how to best proceed.