My ideal situation is realtime updating of both systems but I don't think quickbooks supports a "push" in the same way we can with ubercart.

In implementation (if possible), I plan on having ubercart update qb at the time a purchase is made. Then having a hook in the cron job system to have it make the necessary adjustments that way. I would like the option to just keep inventory there and not have it disable the add to cart in case someone has a drop ship system setup where it doesn't matter if they have the item in stock or not. Does that last part make sense? If nothing else I will use cron to update the inventory along with some options to say only update quickbooks, ubercart or both.

What are your thoughts on this issue?