I can't see how the halti restricts shoulder or leg movements as it's a head collar based on the same control as a horse bridle but I don't know enough about canine anatomy to say that is true or false and I've not heard of that before. I have heard people suggest they are not good for the dog but in some cases, when you risk injury to yourself and have exhausted all forms of training then there isn't much choice.
We had to resort to halti with Bonnie as her 14kg pulling seriously hurt my shoulders and caused severe back pain. Whilst I'd say Bonnie is happier without the halti, she is always fine, sniffs as much as normal and walks without causing us injury. As the majority of Bonnie's walks are off lead, I don't see it as a bad thing at all. She has it on for a maximum of 10 minutes before she gets let's off, has a good hour and more running around, then 10 minutes back home with it on. She also has a walk without any lead at all most days as well because OH takes her to the woods in the car. I would say that if it's mainly street walks with no off lead time then I'd probably be more averse to using it.