Hi Mike,
Setting the Default value of a YesNo field is actually a screen level action. Meaning you are just checking or unchecking the checkbox by default on the screen you are using to add/modify records, and actually has no bearing over what the default insertion value is.
So to answer your question, if you were to add an item into QuickBooks, It will sync over with your method-only YesNo field (IsIncludedInReport) set to FALSE. There isnt a way to sync these records over with the value set to TRUE by default, you would have to alter the records once they have been brought into Method.
Another thing that is worth mentioning, although im not sure how much use it will be in your sepcific scenario, is that Method will sync with QuickBooks Custom fields on the Item table. Meaning you could add the IsIncludedInReport to QuickBooks as well and set that to "Yes" by default and it would sync into method as such. There is one fairly limiting factor however, is that the SDK limits us to only Write new data and read Existing Data to these fields, but not modify existing data. This would mean that if you were to modify any the data in these fields after a records creation, QuickBooks would reject the change and the data in method would be "Rolled back" to reflect this.
Hopefully this clears things up. Let me know if I can be of any more assistance.
Thanks Mike.
Regards,
Ben