I have the T.Touch harness for Ella, but only use it if we are on our own as it is almost impossible to walk three dogs together with one of these on.
after being shown how to use it properly at a workshop, and then trying it at our training nights, it does work, but it is getting your head around NOT pulling back on the lead, Although I do use the halti double ended lead with it.
if your shoulder is hurting then you are walking with a stoop towards the dog, you have to walk upright and not look or twist down and towards them, as before, training the owner is what takes the time!
I have this trouble!
hope this helps a little!