This would hold true as long as the new wheel tire combo is not heavier and you are just cruising at constant speed on the highway. A larger diameter usually involves a slightly heavier rim (than the same type of a smaller one) since it's more metal. Plus, you're moving the weight out FURTHER from the center of the rim, which creates more rotating mass. So yes, you are correct that acceleration suffers because it takes more power to get those rims moving and up to speed, which also would decrease gas mileage over the previous set up. However, if you are just looking at cruising speeds, a larger overall diameter would theoretically get better mileage, although it's negligible.

The reason I stuck with 19s on my car and not 20s, was simply because I do 80 miles of traffic-y driving each day and I didn't want acceleration or mileage decreases due to the weight being further from the center of the rim.

 

Helps with lane changes.