In my opinion, there's no reason to prefer RF other than the looks. The sundownz amps are more efficient. They have a subsonic filter that is useful, and they don't charge you for their name or aesthetics that don't help the performance of the amp. So in short, if you like to waste.... Meaning waste MONEY on the RF name, and current due to RF's inefficiency, then you should get the RF. If you just want an amp that puts out power over it's rated and does it extremely efficiently then get the sundownz.