I'm running a website, and would like to get a better idea how many subscribers I have. I can check the number of subscribers on Google Reader for my two feeds (RSS and Atom). I also have access to my server logs, so I sometimes collect all the IP addresses that access the feeds over a month or so and do a uniq.
Is that an accurate way of doing this? Are there other feed aggregators that I need to take into account? Any pitfalls when just going by IP address?
I've also thought about embedding an image in the feeds to get a better count. But do all feed readers load images automatically?