I use it on my Lakers blog, but I have only gotten one click on like 900 impressions. You may have a better luck with your niche though. I heard that MP3 widget converts the best regardless.
Here's what the Google AdSense Program Policies has to say: Competitive Ads and Services In order to prevent user confusion, we do not permit Google ads or search boxes to be published on websites that also contain other ads or services formatted to use the same layout and colors as the Google ads or search boxes on that site. Although you may sell ads directly on your site, it is your responsibility to ensure these ads cannot be confused with Google ads. I read that as a yes and I use the two programs together with fantastic results.