another possible issue to consider apart from the increase in thickness is degradation of reception which, with the E71 at least, posed a problem for many users.

Here's a picture from a series I took of the E71 aluminum PDair case.

While the aluminum clad E71 was acceptable since it was very thin to begin with, I found the thicker devices I had did not fare as well. Three instantly come to mind: the E90, Glofiish M700, and HTC Kaiser. Since the N900 is of a similar thickness I am not willing to give these cases another chance.

Looking forward to future reports about thie N900 PDair Aluminum case.