MOz, I had this dilemma last week. Took mine in for a service and asked instead of an XE if I could demo the AWD V8 they had outside. They gave me it for 1.5 days, so I took the liberty to use the 250 miles they gave me to take it into Wales... why not eh?!
Don't get me wrong I adore my V6S, but the noise, the torque and the power that the AWD V8 puts out is phenomenal. I've heard so many say the V6S is the sweet spot, and the V8 is too much to handle on twisties, but in the AWD guise I found the V8 managable and all the fun of the V6S and more. The noise (even though it is a artifcial noise) is monumental, the torque wins above the V6 as you get longer gears and are changing alot less when hooning it on the twisties and you don't feel like you are over-revving the engine half as much. For sure the RWD V8 would be a different animal and I'm sure I would agree that is wouldn't be as fun as the V6S, but in AWD guise I find it hard to fault.
I got back to the dealer, beaming smile, started talking about the price differential between mine and the 2015 AWD V8, and its just too big a gap for me at the moment sorry to say. One for the future. I'll just have to "make do" with only a V6... :lol: such a first world problem.