The most important thing with podcast statistics is to host on a services whose main function is podcasting and that offer up podcast specific stats package. Make sure they filter stats to take out duplicate requests for downloads as well. If they are not applying some algorithm to their stats they are not going to be accurate
Straight server logs from most website hosting type services do not adequately count downloads for podcasts - they tend to way over inflate the numbers.
Look for a service like Libsyn.com which is just for podcast hosting for your stats if you want to get an accurate count of your downloads.