I am having hard time imagining who's going to pay $5 a month for this and yet don't bother using registrar's own page editing tools, which are routinely available for free.
RSS and maillist support are nice, but I don't think they add to much value to the proposition. If I am expecting a pre-launch hype, it likely means that I have a marketing budget and therefore I can certainly host temporary landing page myself.
In other words - I'm not sure about the customer acquisition and conversion strategies. I just don't see qualified paying customers between your potential users.