Sorry, I did not see this thread earlier. I use phenolic plate to make motor mounts. The only trouble is proper orientation, it consists of layers and they must be perpendicular to screw holes or other machining, otherwise it separates.
The advantage is clear, it very well bonds to epoxy or other glues, it is strong, it does not soak oil, it will last far stronger compression under temperature (from engine screws) and it even allows to make threads directly in the material
Disadvantages are also clear, the worst is the weight, so I use relatively small pieces (in crossection) and I use lightening on back side of motor mount. If I remember well, the weight of both pieces was almost 2oz. It needs machining as it is relatively hard and I cannot imagine to cut it out manually.
I do not see any ill effects of its strength like aplilifying vibrations or so. It is closed in balsa sides, ribs.
The construction is visible on some pictures here:
http://www.rcmodely.sk/F2B/