Here is my insight, having had a 2014 wagon and now a 2015. The 2014 had the first pre scandal reflash for emissions, it was a terrible tune that went from one regen per tank to 4 or 5. Regens are terrible, the engine runs extremely hot and the more heat cycles the sooner things like turbos die. I was seeing temps of 1400-1500, it also did many mini regen events inbetween and the throttle would be laggy like a sudden head wind or a/c compressor kicking in, it was not an enjoyable car to drive (dsg). The 2015 only hits 1250 on gens so far, not near as hot.
Now with the 2015 and the first stage fix, the DEF really helps. No mini regens ever and generally one full event per tank, fuel economy is much better by 5-10%. Running up to the cottage last weekend with the car loaded (3 adults, 2 kids plug luggage area full to the roof) Kemptville to Tremblant which is not a flat route was 4.5L/100 going up and 4.2 return, the 2014 never did below 5 on that route. It would hit 4 going to Quebec city but that is really flat and the car was empty and I tried really hard. The extended emissions warranty is better on the 2015 by a good amount. Having to add exhaust fluid vs the fuel savings is pretty even but the driving experience is much better in the 2015, plus the level of electronics and features is light years ahead even the base trendline model. 2015 can run 15" tires which cost less and are available in narrower sizes for snows.
The only downside with the 2015, it follows truck ruts really bad (on poor Quebec autoroutes), really really bad like the road is slippery but not. If it was slippery I imagine it would slalom down the ruts pretty easily, not sure why yet if alignment is the issue or the rear torsion beam-it is not tires as both 2015's we got do it and each car has different summer and winter tire brands.
I am very pleased with the 2015, very very pleased. Plugging in the Vag-Com there are over 700 features that can coded to your liking...all in german of course!