it’s less from a developer/marketing perspective but more from a “prominent author” perspective.

No, it's from a "proposals are unlikely to be approved today, what could increase the appeal of a proposal?" perspective.

an up-front payment

No, please don't get hung up on this "up-front payment" thing, that's not what I'm talking about. (Also, if we're hypothetically talking about funding writing rather than code development the output of the writer is much more likely to be showing up on the chain in a way that can be evaluated on an ongoing basis than a coding project where the developer can plausibly claim to be doing things but not be ready to release the code yet).

I’d be inclined to say it’s more risky since the money’s already gone. Using my proposal as an example, if I down tools / leave the platform, the DAO can stop payments whereas if Steemit was recouping the same figure from author rewards, it would never retrieve them.

No, it's the same. If you disappear you keep the money and never provide the deliverables. If the hypothetical person running a proposal where they promise to do something and also pay some money to the DAO disappears they keep the money and never provide the deliverables. There is no way that "plain vanilla proposal + pay $X to the DAO" is more risky than "plain vanilla proposal", even in the worst case scenario where X is 0.