David,
I too was sorry to see the back of my 850, although my brother in law has it so its still around! It was a T5 with all the toys which all still worked at 120,000. Even the air con! Downside was the 18 mpg with the van on the back! I am very pleased with the D5 I have. It is three years old and therefore the 163bhp. I can also change the headlight bulb without having to remove the front bumper. this is required on the 2005 model year. I am getting 42mpg according to the computer, diesels seem to suffer economy wise when fitted with auto. But I am of an age and the traffic these days is such that I prefer the auto. I tend to let the gearbox do the work at the moment, but once I get the van on the back I will probably make more use of the geartronic. The 850 would drop out of top gear on any hint of an incline, so it will be nice to have a bit more control. When overtaking the gear can be selected rather than rely on the kickdown. Handy if you can anticipate the overtake. If you are thinking of a D5, avoid the early ones as there expensive problems with the injectors, although I believe volvo are coughing up. Mine is the 2004 model year and isn't affected by this.
Good luck
Gary