The big catch here seems to be the thermal capacity. Moving five watts of heat for one watt of input power doesn't sound that bad until you realize that current heatsinks and axial fans are ten times as efficient. The system I am sitting at now needs to move about 800w of heat at maximum load...and it does this with fans that consume maybe 15w total.
Scaled up, the amount of vapor chamber surface area that will need to be cooled will still be prohibitive (using my current system as an example again, I can get the AD102 chip on my video card itself to consume ~500w, which, if I scale up the larger, 10w, cooler shown, would need a vapor chamber about the size of a pizza box) unless it's given a more conventional fin stack, in which case it will loose it's advantages with regard to dust and noise, while still requiring far more power than low velocity air delivered by axial fans. There are also some redundancy concerns; the smaller a heatsink gets, both in mass and surface area, the less of a thermal buffer there is. Shouldn't be hard to always use multiple modules, and modern hardware can throttle so fast that even loss of the entire cooler usually isn't dangerous, but having a system slow to a crawl or trigger a thermtrip because something blocked airflow for a second or two could be annoying.
I'll need to see a scaled up version actually cool a major thermal load, silently and without having to be in an absurd form factor, to be sold on it for non-mobile use.