I know several owners do use and like the martingales. I'm just not a fan.
I had a martingale for Jazz; actually still have it,I just don't use it.
I found it did flatten the hair on her neck.
When I take the rolled leather collars off, there's no sign there's been a collar on. When I removed the martingale, there was a clear line for sometime indicating that a collar had been there.
Do you not have the same problem?
The martingale does tighten on the neck when the dog pulls, but I also find that I don't need that aspect as it was no more effective in stopping a pull than the leather. And since my dogs are always ahead of me when they are pulling, there's no chance that they will slip out of the collar. {They'd have to kind of back out of it}
I also like that the rolled leather are less visible on the dog.