We have two dogs - 6yr old German Shepherd [censored] and one of her sons, year and a half. Originally purchased for security reasons, Skye, and now Arran are both part of our family providing security AND companionship. Both dogs need lots of exercise, and it takes a 40 minute drive to take them out into the desert where they can run and roam freely (there is nowhere in the city we could do this).
I'm starting to ramble a bit, but what the heck - We take them on regular camping trips, in fact we are off again this coming Thursday for 3 nights, and in the beginning, I used to secure Skye to a 60mm piece of re-bar driven into the sand. Any time a bit of wildlife came by she would bark and howl, waking us up several times a night. Nowadays, we leave them loose and they lie on a groundsheet spread beside the tent and will chase anything coming by, then return to their positions. I would say that they recognise their duties, and they are on guard. This usually does lead to difficulties the next day if we want to go off wandering, as they are normally too knackered to walk far as they've both been up all night !! <img src="images/graemlins/grin.gif" alt="" />
On other occasions, we have been hiking up and down the wadis when a pack (10 and upwards) of wild dogs have come over the hill, and our two have seen them off, although I must say it has taken me up to half an hour to get them back again.
My two are not by any means "trained", although they are as obedient as any 10yr-old child !! <img src="images/graemlins/crazy.gif" alt="" /> However their instincts are "To protect and to Serve" and I wouldn't be without them.
During daylight hours I have to be pretty alert (your country needs them <img src="images/graemlins/grin.gif" alt="" />), and if their are any people about (highly unlikely, but does happen) call them to heel.
One small item I would add is water. When out walking, say for an hour, my wife and I carry a litre each for ourselves, and three each for them as they cover so much more ground as us and don't have they same biological systems for dispersing heat. You could say that WE share THEIR water !?!!
My last thought on the original post - they're a great addition to your PSK under the right conditions.