The Inov8 Debrisock are a great idea – combining a technical running sock with a gaiter unites two pieces of trail running equipment into one convenient item.  I ran the Bogong to Hotham ultra in January without gaiters and ended up with a few pebbles which led to some nasty foot issues late in the race.
  The Debrisock are comfortable as a sock, and at 38g, they represent a very small weight increase that isn’t noticeable.  The gaiter fits neatly over trail runners, and while wearing them, they totally eliminated all issues with burrs, stones and twigs ending up in the shoes.

 
  The problem with the Debrisock is the metal catch that attaches the front of the gaiter element onto the laces.  The problem should be evident when you think about it – take a thin piece of metal and rub it against a lace a couple of tens of thousands times as happens in the natural movement of the gaiter against the shoe that occurs in running.  The lace rapidly wears through and snaps.  In a long trail race, this could be an absolute disaster from a racing perspective. 
  My Debrisock took about 100km of trail running to get most of the way through the Kevlar laces of the Salomon XT Wings (photos below), and at $20 a pop to replace the laces, going through the laces that often to continue wearing the gaiters isn’t worth it.

With the Debrisock not doing the job for me, the next product I’m going to try out is the Salomon S-Lab Gaiter.  As with a lot of Salomon products, these are ridiculously hard to get, and going for a cheap cotton camping-store option for the next ultra (TNF100 on 14 May) will be the most likely option.  If you are still keen on a pair you can pick them up for around $15 on Wiggle.

Overall Rating: 1/ 10 (and the 1 is an encouragement bonus for some nice lateral thinking that almost produced a usable product :))