However, why would you need a c-corp to accept investment? An LLC provides a lot more flexibility and you'd just have to redo you Operating Agreement.

That flexibility comes at a price, an investor can and likely will insist on modifications that provide him greater protections/rights/whatever that he would have been able to get with an investment in a c-corp. I've worked for one promising company who's life was cut short when its devil investors abused various provisions they had put in the Operating Agreement to gain complete control (all of nothing, we all resigned, but they didn't seem to mind).

Investors would almost certainly want vesting terms. I'm not sure that is possible under LLC.

I think you need to talk to a lawyer in your state who's familiar with LLCs and out of state c-corps to know what's possible and what it will likely cost (unless you live in Missouri, in which case I can ask my father).

Note also that a less flexible c-corp might turn off savvy investors (the type you want).

Since you might want to raise money, to me it seems like the most intelligent thing to do would be to set up a Delaware corporation and operate as a C-Corp. After that if you decide later that you will NEVER want to raise money then flip it to an LLC on advice from your business tax person.