Thanks boys, you've made me feel at home already
To answer the questions:
Why the change from the Q5. Well, I love the Q5. I think it looks better overall and the build quality is definitely superior. However, having owned it for a year there are two things that I can't get on with: 1) The suspension kills me. Its S-line with 20" wheels and I curse it over the potholes every time I drive to the station and back. 2) The 4-pot, even in 170hp form, is underpowered for a car of the size. No offense meant (and each to his own) but the X3 20d is the same. Never struggles, but never really goooooooooes. I am a bit of boy racer at heart and I can't deal with Golfs or Fiesta Z-techs staying in my mirrors when I join a motorway. I pondered changing for another Q5 in 3.0tdi form but that seems a bit boring, plus I've always loved BMWs for the fun factor (I have owned a couple in the past and current have 118d as a second car) and the straight six diesel, even in vanilla 30d, is an absolute gem. Sport mode, foot down and you think you're in a sports car. Seriously, not had as much fun in a long time as I had a fortnight ago in a 30d for the day.
In summary vs Q5:
Q5: Better build quality (unquestionable- just look at your storage compartment made of cardboard under the steering wheel and that terrible rattly plastic boot cover in the back of the X3, you would never find this in an Audi), better looks (totally subjective!)
X3: Far better engines and tech, much more fun, much better choice of interior colours (Audi Sline is black, black or black).
On the spec: contemplated a 35d for a long time but that you just have to have in MSport (no one will want a used one in SE) and, to be honest, I just dont like the Msport. The wheel choice is not that great and it looks a bit too chaved-up for me. Totally subjective I admit!. I prefer the Mineral Silver which is not available in MSport and I dont want the sport suspension nor do I want to pay nearly a grand on top for the toy suspension. SE suspension with Performance control and Servotronic coupled with the 30d will really be a wolf in sheeps clothing. I would have loved the 19" wheels but the premium is silly if you don't add the Dynamic Pack (which would add the sport suspension that I dont want).
I'm really happy with my choice and hope that our friends over in South Carolina get around to putting it together (carefully) soon!