I would say that I predominantly in Eco-Pro but that's only because I'm on the motorway and so just cruising along. When I am coming onto the motorway or am going for a half gap then Comfort or Sport modes come into their own
When I get off the motorway I'll switch to Comfort for driving around towns or into Sport for when I am approaching a roundabout/junction just in case I need the extra boost.
I think the most I've achieved as 'bonus' miles from Eco-Pro has been 27 which was from a 550 mile tank of fuel so a very poor return but I'm sure they will all add up eventually. When I have driven in Eco-Pro mode after coming off the motorway the 'bonus' miles go down so there doesn't seem to be any encouragement for town use
Overall average on the brim to brim calculations is currently 51.9 mpg which is about what I was expecting based upon my mainly motorway miles. The Journey computer that I reset at each fill up always shows the mpg to be in the mid 54s.