I read a review / test of various compasses several years back (sorry, can't remember where I read it).
The military lensatic compass did not do as well in the ruggedness department as the other plastic models (Brunton and Silva).
As I recall, the rugeddness test involved stepping on each of the compasses to see how they would hold up. The lensatic compass did not withstand the test in tact, whereas the others suffered only minor cosmetic damage and were still functional.
Also, the lensatic compass is not waterproof.
Although the lensatic compass appears to be more rugged than the plastic Silva and Brunton models, these tests seemed to indicate that the opposite is true.
Maybe someone out there saw the same article and could provide a little more info.
BTW, I like the Silva Ranger.