I think Givenchy Vetiver is a masterpiece and better than Guerlain imo. I'm not sure what you ask, if they can replace niche fragrances? In terms of quality? I don't think niche fragrances are necessarily better, they are just more creative, or odd if you want. So, designer or niche doesn't matter, designers can contend with niche and vice versa. It boils down to the specific scent and how it works for you.