According to CNET's recent article, WMA DRM caused a 25% reduction in battery life in your portable music player. This seemed fishy to the guys at DAPreview, so they set out on their own test to see whether this shorter play time actually held true if the bitrates were the same in the WMA and MP3 files. Turns out, the non-DRM version scored at 14 hours and 55 minutes and the DRM version scored at just 25 minutes less with 14 hours and 30 minutes. A 2.8% difference isn't going to get people riled up anytime soon. Looks like you've got red on you, CNET.
Battery Test: DRM vs. Non-DRM [DAPReview]