> The question really is if straight utility pricing makes sense. I could imagine that a floor on the pricing, or a non-linear curve would probably do better than simply keeping the same model and raising the prices.

The question is if the costs of running tarsnap correlate exactly with the amount of data that is stored, or if the number of users also have to be factored into the equation, ie. if each additional user has an added cost. I would say that in a business like this, with a low barrier to entry, the price should reflect the costs as close as possible. So if there's a constant setup cost for each user, the price shouldn't be $X/GB, but $X/GB + $Y.

Ideally, Tarsnap should make the same amount of money from a single user storing 100 TB and 100×10^12 users store a single byte. If this is not the case, the pricing structure is suboptimal.