Your project shouldn't grow bigger in terms of how much delegation you're getting because you're making sure to keep your delegators happy with upvotes no matter what they post - but because your project is better at what it does or plans to do than others

I think, you nailed it right at the end, the reward of holding the zing tokens would be visible, when the project goes live and does well, increasing the price of the token. That's the real reward of a project performance, not just delegation.