Apologies for linking to an AAS comment thread already half-linked below, but an AAS user has been doing battery benchmarks for two N95's, one with old v12 firmware and one with the new v20 with DVFS (Dynamic Voltage and Frequency Scaling), it seems that for low-CPU tasks like music playback, the battery is used more efficiently, with the underclocking resulting in 20% longer battery life from the BL-5F.