I've never heard of it, so please let us know what you decide, and give us a follow-up.
Swim therapy is pretty much the best exercise, but not always available. I do walk Maggie a mile or more every day, with her harness on. The leash attaches to a loop between her shoulder blades. I encourage her to "walk on" ahead of me, letting her keep tension on the lead. Her physical therapy vet said that this forces Maggie to "rebalance", getting more of the weight off of her front legs and onto those rear legs, to make her work and build the muscles in her rear assembly. The vet highly recommends this exercise (walking like this, in a properly fitted harness) for dogs with HD.
FYI: the harness our vet gave us to use is a "Premier" brand "Sure-Fit Harness", in size XL.