Omni is less expensive than King Tut because it a polyester thread as opposed to long staple Egyptian cotton. I have never used Omni as I prefer a high sheen polyester (Omni is a matte finish) and when I want variegated I use King Tut. The only variegated I ever had a shredding problem with was Superior's old line called highlights. Apparently it was a universal problem as they discontinued the product.
As Paper Princess recommended,you definitely do not want to use a variegated in a quilting design where you have to back track. It gets unsightly very quickly. But it looks wonderful in designs where they are continuous and have no or very minimal back tracking.
If you like using a variegated in your longarm you should give the Omni a try. Other peoples experiences with the product may not be the same as yours. I know some people who love using Omni and others who can't stand it.