Ask HN: Pay What You Want SaaS?

I'm curious what everyone here thinks about a Pay What You Want SaaS revenue model. To me it seems like if the good that you're selling doesn't have much material cost, then letting users decide on a price could be a good way to get people interested. It also hopefully means that fewer people would not buy it for price reasons. Obviously, if your product requires lots of support or server costs, then this is much less feasible, but many SaaS products have a low cost to produce. To mitigate fixed costs, you could set a price floor.

Despite the appeal of this revenue model, I couldn't find any other examples of this revenue model - are there any other companies doing this? If not, why not?