You're reasoning is valid and makes perfect sense.
My kids are 12 and 14 so don't have an issue with the high window line - the 14 yr old is 6ft 1" and he said the trip to Belgium recently was very comfortable and mine's a Coupe.
Space is an issue for the longer runs for us too but roof rails, cross bars, roof basket and two large waterproof ARB bags solved this comfortably. At the other end the bags remained off and the car fitted in underground carparks no probs.
I've got the Si4 so economy wasn't a main priority - given my commute is only 16 miles a day. I'm averaging 23/24 mpg for the urban commute which is what LR say's it should be and my D4 was about the same. But the Si4 engine in the Evoque is very nice indeed and in Sport mode I'm not having any issues with the auto changes. I would say in normal drive mode the auto box does exhibit moments when I would prefer it to change and it needs extra encouragement but then so have most auto's I've driven.
I have the dipping mirrors but they are turned off - I park my car next to my wife's Mini in the garage and it is a relatively tight squeeze to ensure enough door opening space so prefer not to have them dipped. I've not needed to parallel park as yet so it will be interesting when the time comes although I could try the auto park feature.
It's early day's but so far I'm happy with the downsizing from the D4 in favour of a more enjoyable driving experience. I have opted for a full-house spec and it does make ownership more enjoyable; I'm wanting to keep this one longer than my previous cars so decided to go for all the toys to keep me happy.
It does attract a lot of attention too - parked comfortably away from others at Sainsbury's this morning only to return to find two Gents and an elderly Lady admiring it; they had waited for me to return to discuss the car and voice how wonderful they found the design!
A BMW X3 will be more practical and economical and they have a better range of engines - superb engines - but overall I'm sold on the Evoque for its character and design and have made it work for me in terms of space etc.
My wife's Mini has character, my BMW's had fantastic, efficient engineering. My D4 was a brilliant large Family car but the Evoque does seem to have the character the Mini has which makes it more endearing to me