There are moving parts. But flash component can be used as a buffer or cache as you said, to store the frequently used data. Then the magnetic component can be turned off until files on it are needed. Power consumption will be low as flash drives are very energy efficient. Good for laptops. There is a huge flash drive with 32GB capacity, but I don't think it's released to the market yet, or if it is released, it's so damn expensive. 2GB are around Rs.5000 no? And this price is not for the fastest drives.