Most species of maple are notoriously difficult to root from cuttings, particularly cuttings taken from mature specimens. Given that, I would make use of whatever rooting hormone (and the cloning gel is essentially a rooting hormone) available to gain as much of an edge as possible. And research the best timing and method for each species attempted.

What are the active ingredients in that gel? IBA is what is used for Japanese maples, i have a reference manual that says NAA is inhibitory not helpful. Although i know a lot of people use dip in grow which has both hormones. Ive done japanese maple with hormodin 3 a strong IBA talc formulation I think it's 8000 ppm. Since IBA works K-IBA should be even better but it's expensive and harder to find. Maples are not easy to root, but most can be rooted if you know how. Grafted plants are often more vigorous, make a plant that can be sold faster and that's how they are usually done. someone who is good at it can get a very high percentage to succeed. Rooting cuttings is slower, and success rates may be low, 50 percent or less.