Never heard of an Attitude before. But just by googling, I'm guessing you're talking about the Eclipse Attitude. Correct? But comparing the companies, Grand Design is far more successful than Eclipse.
As far as the Momentum, only heard great things! Like the 60G pump station comes in handy when traveling with quads/'toys' and the dual entry is great for entertaining guests while keeping your distance from the unlikable guests. You can get up to 3 awnings expanding your horizons. Lots of features, even ones you didn't think you'd want... like a diamond plated garage so your toys don't scratch it. Like who would have thought of not scratching their garage? Not me. LOL