I have a 2010 3.0D V6 have had it for 2 years 55000 miles on it and no problems. I would go for the bigger engine has the fuel ecomony can be better than the 2.2. You must remember people only post when they have problems they never post and say another day trouble free. XF's do suffer with electrical gremlins but are normally fixed by just turning off and back on. Just make sure you have service history and cambelt/chains if high mileage.
Just passed MOT last week at the dealers and nothing mentioned. VOSA say if they dont have self leveling and washers testers should err on the side of caution and pass the car. Still a very grey area though, the next one will be about LED's I'm sure