Is it true that you may enter the funding cycle as an LLC but that as a practicality you won't exit funding as anything but a C, that angels and VCs will insist on this restructuring? I think the answer is yes but I don't know.

Can someone price the cost of converting a Delaware LLC to the C structure that VCs will expect? I think (again, I don't know) that we're talking about a couple of grand of post-money lawyer time.

Early stage startup founders have a lot on their plates. Getting this nuance right to save a few bucks will cost some upfront neurons and some time for something which is ultimately procedural. The OP suggests that we mentally work through this ahead of time and I see the point. But it's like priced equity vs SAFE. It requires a lot of upfront neuron work.

The LLC vs C tax issue seems to be a bit of a canard. You most likely won't have any profits to tax this early and you won't exit funding as an LLC.

Anyways, as the Zuckerberg Florida LLC example shows, you can get these things slightly wrong and still move forward. Getting something infinitely right will guarantee that you will never move forward.