ruthless,
I've been reading your thread. You're not alone!!!
I have a two year old Lab and a 2 1/2 year old Border Collie (rescued 8 weeks ago) and they are ABSOLUTE NIGHTMARES to walk!!!
Max the Lab particularly pulls me to buggery, and I have arthritis in my spine, so it's absolute agony to walk them. I tried so hard to be the best 'mum' ever to my boys, and took Max to puppy pre-school etc from the very beginning. It's just his one big fault - actually, I guess it's my big fault.
I've tried many of the things you have, haltis, stopping and turning around everytime he pulls etc., and we get about 10 metres down the street and back and forward till we've worn a track in the grass. It's so frustrating, and I get so impatient when I'm tired and in pain and they make it so damn hard on me to just walk them!!!!!!
Consistency is definitely the key, and area I've fallen down in too. (I often end up giving up and just letting them off at the park for a run)
I feel inspired though, now that I know I'm not alone. I'll try (again) the techniques other forum members have kindly offered, and hopefully soon walking them will be a pleasure, instead of the nightmare it is currently. Good luck to you too!!