The pulse device sounds like it will do well to ventilate the whole case, but not to cool a quickly heating cpu. The air flow will be spead out throughout the case and not concentrated in one area which has a very high rate of heating. If this accordian device was ducted to the cpu (volume of air narrowed to a small outlet, thus increasing flow rate per area), this may help depending on the volume and frequency of the pulse. The total flow rate hasn't changed but, the flow per area has. Without ducting, the air is distrubted to other areas, whereas ducting (narrowing the outlet) directs all the air to flow in a smaller area. In this case, this is analogous to a regular hsf blowing on then off. Also, a one way flow is is needed to prevent back flow of warmed are in the reverse pulse. I'm no thermodynamics expert, but a cpu would probably need a faster flow than than can be provided by a slow pulse of air spread throughout the case, unless the volume is really large.
Now consider the above isn't a factor for argument's sake (either it's ducted or the volume is sufficient). Another variable then to consider is the threshold of failure. Imagine a cpu heating so fast it fails after a short time between pulses. Imagine the same cpu with an equivalent but constant flow. In the latter case, the cpu may never reach critical temp since heat is constantly removed though the total air flow is the same within a given period of time. In a cyclic flow, the time period must be tuned to the failure threshold.
Now, if you aren't trying to cool the cpu, but just the case temp, then you may be successful if the total air flow within a time period is the same in the accordian method as in the constant flow method.
Also consider you'll need a movement source (simplest would be a motor) to drive the oscillation. A quiet motor is a must, otherwise it defeats the purpose.
Also, consider that much of the noise from a case comes from the powersupply and cpu fan. Quiet power supplies are available as are quiet cpu hsf (especially for celerons). ONce you quiet these, the chipset fan, gpu fan, and hardisks be heard.
Just some ramblings.
Quality is better than name brand, even regarding beloved AMD.