The HS is still probably a good 2 legged round, but it's not really a 10mm, more like a 40+P.
Which is exactly how the . 40 came to be. Most people wouldn't shoot full 10mm, so it was downloaded. Some genius decided that it could be put into a shorter case, and therefore into a smaller gun. Viola, the . 40 S&W. Just the opposite progression of the . 38/. 357 magnum.
I mentioned using the HS as a carry round because you said that your wife would be using the G29. I don't know your wife, but I assumed, like most women, she would be dis-inclined to shoot full house 10mm out of the smaller gun. Full house can be a handful in the G20, for many.