I bought mine a few years ago and love it! It definitely has some power. I use the extra channel from my Samson Amp (350w per channel), the other channel drives my SVS subwoofer. In my opinion, you cant go wrong for the price! Although it is not in the same league as the buttkicker line, its definitely a huge step up from the Aura shakers. The Clark doesn't go as low and isn't as powerful as the buttkicker, but does a great job for the price.
If I was to spend $300-400 on a shaker, i'd definitely go with the buttkicker. Otherwise, you won't be dissapointed with the Clark Synthesis silver. I have a 9' 1/2" by 15' 0" x 13" high riser and it literally feels like the riser moves up and down during LFE passages.
P.S. Definitely go with the clark synthesis.. I just looked at the price of the aura's !! PM me if you have any specific questions