I'm kind of liking the flat/threaded.
It allows the listing like PhrankyB is talking about, yet still offers the threaded style once you enter the post topic.
This might allow some of the entrenched folks to adapt and then allow a pure board style later, or...we may like to try something else at a later time?
I'm thinking keep it simple initially then tune it as we get the folks used to the 19th Century....= )
What say you JimD? How does it effect loading time?