Compare Feedburner Feeds With Feed Compare
Feed Compare is a fresh service for comparing Feedburner feed subscribers.
This feed comparison application lets you compare up to 4 feeds at a time and presents the results with a nice flash chart interface (amCharts).
Feed Compare is great, not only comparing the end numbers but also for viewing the subscribers in a timeline (max: 24 months) to analyze the feeds of similar sites better.
P.S.: Thanks for the guys at Feed Compare for the suggestion.