I have a 338 lapua and not Norma but it shouldn't change my answer. 300 gr Bergers are most definitely considered superior to smk's. However depending on your budget and your expectations, the smk's can do just fine.
As far as the two powders go, I think both are considered great powders for our calibers. I started with h1000, couldn't find a good load and tried retumbo. Ended up finding a load with retumbo and stuck with it. However , I might have just not given h1000 a fair chance, bc I also changed my brass at the same time, and I think it was my brads that the issue. You would probably be just a well of with either h1000 or retumbo.