I've put about 100 miles on it so far. The SOTP dyno feels pretty similar performance wise. It is quieter and a little smoother at idle. Stop/Start is going to take some getting used to. Ride/handling slightly better. Like pushing the shifter in the 14 better than the toggle on top of the shifter for manual gear changes. Over my city/highway loop the 17 shows about 1.5 mpg better.
Quick update, The 17 has 2500 miles on it now. We did a road trip to the Texas panhandle. Best 25 mile average was 60.3, Best 50 mile average was 56.6. Ride comfort was better than the 14s. Real world performance is about equal between the two gens.
The dealership finally got the 18 Diesel RS hatch. The red one got traded in today. Pics after sunup tomorrow.