Why do you like it on the body better than the heel?
Does it hang straighter?
Yes, it does hang straighter. Feels much better. With deeper archtops, always feels to me like the body can tip away from me, when the strap attachment is at the heel. Not well balanced. With thinner hollowbodies, the heel spot works fine. My luthier suggested the rim attachment with the Silvertone. Good call. Feels perfectly balanced, and no twist to the strap as it goes over your shoulders.
My deepest archtop now - a vintage Guild X-175 is not quite as deep as that ES-175 you're looking at. The Guild has the strap button on the rim; I'm happy to have it that way. The Guild is no doubt heavier than that Gibson. The weight hangs from the strap attachment points straight down. Feels more secure than it would be to have the weight all in front of the attachment point at the heel.