Ideas that spread, win, and that IS about passion. A great idea, even when it targets a niche and allows for significant sharing among the "sneezers" of your consumers, needs some passion behind it for those sneezers to care. I think there are a lot of niche products, and the smaller or narrower that the niche is, the more likely it is that the "sneezers" will need to sense a passion for the idea because they themselves are more likely to be passionate about that topic. Remember, the "sneezers" are "the experts who tell all their colleagues and friends". They are the experts, and will want to feel similar interest in the field or topic.
The sneezers are the first-adopters. They are the trend-setters for their field. They can also become your brand-loyalists and can provide leverage into your target segment for quick penetration of the market. The sneezers can also be very useful to tell you what isn't working about the product or service you are offering. This can be a way to build brand-loyalty, and is essential to keeping brand-loyalty. As we have studied from Sernovitz's book it is important to treat people well, be engaged in a conversation about the product or service, and be responsive to their feedback. So utilizing the "sneezers" for continuous improvement, to develop your strategy based on real input, or to check how you are executing that strategy is a useful thing that can pay both in the information and in the true engagement of a customer.
This position and relationship can augment the word of mouth from the sneezers. If you offer the product or service excellent word of mouth yourself, the Harris statistics show that you might have considerable influence with the market numbers, particularly if you are receiving good word of mouth from the "sneezers". This is one reason why to circle back to passion. If you can talk about your idea, your product, your service, or your business online or in-person and share a very positive light, that will carry a lot of weight with potential customers. This is enhanced by the word of mouth you can garner from the "sneezers" or first-adopters, if they feel engaged in your brand.