The Clark Synthesis Gold Tactile Transducer has only half the power of the Platinum. But you're still going to be sitting pretty with a responsive gadget that does more than most bass shakers.
It has a great tactile force peak than the ButtKicker, which means it's going to shake you even harder in those big moments. It also has a much better warranty (2 years) and you'll be getting the famous Clark Synthesis customer service into the bargain (which I HAVE experienced, and it's awesome).
At $500, the Gold is about $100 cheaper than the Platinum, but has less than half the power. Also on the down side, it doesn't "hear" as low as the ButtKicker or it's more expensive sister, the Platinum. This won't hurt you too much when you're watching older movies or games, but the latest movies, like Cloverfield, drop to an incredible 5Hz (the human ear can only hear down to 20Hz).
All Clark Synthesis tactile transducers have a linear motor, so they respond to changes in volume with incredible smoothness. The Clark Synthesis line was originally developed for the military, so when I say they recreate reality precisely, I mean it. The rising groan of a plane about to take off, or the squeal and smash of a car chase - every suggestion of increase and decrease in power is beautifully reflected in the Clark Gold. If you want precision, power and performance, this might be the baby for you.
Clark Synthesis Gold
Price: $370 from Amazon