BMW X3 Sport or SE 3 or 2 litre?

I have a 10 year old 3 litre X5 diesel which I am looking to change but the new X5 is too big. New X3 is highly regarded but there are very few used 3 litre SE versions as the 2 litre Sport (black!) seems the most popular. Not a great fan of small engine Beemers so my question is whether the 2 litre Diesel is man enough to pull 1560 kg and whether the Sport is too firm a ride for caravanning over long distances? Could I change the rims/tyres on the Sport to get a better ride?