yes I had the same mindset as you, i filed using my previous returns as a guide also done by professionals but the dual status return is not going to be 100% like your other returns. the form 1040 will be similar in regards to how income is reported but there are many rules, for example, one can't claim the standard deduction, or use the "head of household" tax table or file a joint return. there are some other credits that can't be taken.
you have to write dual status return (form 1040nr) and dual status statement (form 1040) on top of the forms. The FEIE is pro-rated.
So if you are on top of the differences, you will be fine. My past returns only claimed the standard deduction so itemised deductions were not something I could work off from.
I had a feeling from reading publications that maybe only the mortgage interest for the part of the year I was a Citizen (considered a resident for tax) was allowed. I didn't claim it to be safe.
And yes it is possible to come out OK. and if you have no ties or assets in the US, there is very little to worry about anyway.