I'm still curious if someone has experience with or thoughts on my original question.
I understand that it's sometimes difficult to dream up a good .com name related to your website content, but if you dream up a catchy memorable name you can always brand it to your website, like you were considering to do with the org. There are a lot of reasonable .com names in the aftermarket for reasonable prices (well if you can find your way thru all the dross out there). Be creative, just as you would in dreaming up an unregistered name.
Never, ever buy a .org if the .com is in use.
Always buy the .com when you buy the .org (and 301 it) or someone else will get the .com and shaft you (MFA or porn).
Quadrille's 15th law: There are very few honest guarantees in this business (plenty of dishonest ones) - but losing out to the .com ranks up there with the best of them: it's a dead cert.