I don't think this word has a negative association at all. Perhaps it has an association of something unproven, unscientific, because it is a belief and not a fact.
It's also sometimes used to describe something done impulsively, without really thinking about the consequences. "I had the notion of uploading naked pictures of myself to Facebook".
I think it's a perfect word for a brand name. Have you thought about using a play on words with "emotion"? Like, "e-notion"? E - electronic, or internet based. Like, E-commerce. Maybe that's a bit too obvious, but it was floating around in my head!