To clear up a bit of a misconception it appears you may have in your question: All carbohydrates are sugars of some sort, either simple or complex. The difference in the body is how long it takes to break them down to be usable as glucose (Body fuel).
To get the answer as to what type you are consuming, you would need to look at the ingredient list, and see what is listed, such as fructose (Simple, fast), high fructose corn syrup (simple, fast), etc. Anything that says sugar, syrup or ends in -ose is likely to be an added sugar of some kind.
If you replace those sugars with oat starch, you are basically replacing sugar with sugar, just in a (most likely) slower digesting form.
My suspicion, however, is that if you say you are eating 440 calories from sugar, and getting that information from food labels, then you are really only counting added sugars, unless you are looking at nutrition facts for raw/cooked vegetables. For example, if you eat a cup of broccoli, you are getting 10g of carbohydrates. 2.5g of that is in simple sugars (fructose/glucose combo), approx 4 g is fiber (undigestible sugar), and another 3.5g of starch (Complex sugar). That makes 6g of sugars, or 24 calories.
As for your base question, if you take out the added/labeled sugars and replace them with slower acting sugars, your energy levels may be slightly lower than after simple sugars, but be a more sustained effect. You may feel fuller for longer as the body takes longer to break down the food, and you may notice it being easier to lose/maintain weight. Each person will react differently. This is a decent basic writeup on the subject of carbohydrates.