I have printed both and they are very different. It all depends on what you want really. I love the Art300 and find MGFB more challenging. I find the Art300 wonderful for toning (but then so is FBMG WT). Art 300 is very punchy and contrasty, heavy blacks and tricky mid-tones. This works for me as I expose heavily, bleach and tone and it ends up looking very lith-like. The Art 300 has a very particular texture, which definitely adds to the overall effect.
Here is an example of one of my prints on Art300.