Has anyone ever used Safer 3-in-1 Garden Spray Insect Killer, Ready-to-use?

They say it has: Contains potassium salts of fatty acids (.75%) and sulfur (.4%) as active ingredients.

Sounded decently safe to use on Bonsai, thoughts?

You can try an insect zapper as well. Usually these kind of spray make the plant go dead. I read about a zapper named Buzz B Gone Zap. Providing the link, you can take a look!
buzz b gone zap

If you must spray then why not use a soapy solution? Much safer than chemical poison.

I have been into the hobby for 5 years and have now about 50 trees. They are decidious, evergreens, conifers from garden center, bonsai nurceries, yamadory and airlayering. There are hardy trees and non hardy trees in my collection.

The only spray I have ever used is neem oil. I spray a few times per season. I would not say never, but It would proboably take a very expensive tree in very bad condition for me to look into poisonous chemicals. Then it would proboably be sulfur burning, not spray.

If I get infestions, I just pick the pests and tries to find out why and correct my care.