A 50GB storage limit is not going to be a problem for most people, but the 100K hits limit is much too low for a paid plan. If you make the HN front page once or twice, you can easily bust that. There really shouldn't be a limit for a paid plan that costs $15/month, but if you're going to have a limit, at least make it based on bandwidth usage, not the number of hits. You're incentivizing successful bloggers to move away from your platform. Is that really what you want?