Elly,
I have used the leashes before on a few occasions for DS. In big places like NYC when Belle was a newborn and we were there for the Thanksgiving Day parade with thousands of other people. I have taken them to WDW before and used them on Belle when she wanted to get out to walk.
Honestly, they both loved it. It made them feel like they had some freedom from Mom...they are so used to having to hold hands with an adult all the time. Belle actually asked for it once.
As for people giving you looks or comments, may be my personality the Wicked Queen coming out, but I love to enlighten those that dare to look sideways at me. When they carry a child for 9 months , go through 8 hours of labor with it only to bring it home and have to raise it for many years, wiping their noses and their butts, THEN, THEY can do whatever they want to with THEIR child. It's no one's business what you do. At least you care enough to keep them safe.
I have seen so many parents not paying one bit of attention to their children while we're there, and it scares me to death.
So, yes, please use them. You will actually have many people say that they wished they had brought one for their child because they are driving them crazy, trying to keep up with them.
Jo