Have to tread through a lot of loose gravel (2" - 6" odd shaped fill) walking to and from work every day. I'm hoping the Vibram soles will stand the test (I'll be here for a year). They're holding up good so far (1 month).  I like the slightly extra padding on the ankles and the grip of the soles.  The adjustable heel insert is a nice addition that I will be trying out over the next couple of weeks.

With the breather vents on the boots, they're good in the hot weather.  Every time you take a step they vent.

I like the sizing too.  I was worried that I would have to order the next size up but I ordered the same size I wore in combat boots and these offer just enough room to be comfortable without creating issues with dexterity.