Hi, the timing belt issues are mainly getting someone to actually confirm the mileage to change!! i'd say the biggest common D4 concern is egr coolers. However, this is common across all brands, so no less unreliable in my opinion. dpf issues, again the same as many brands with diesel engines, the whole industry has issues... The car shares many electrics and its suspension with focus and kuga, but the D4 engine is a Volvo unit, unlike the 1.6 D2 with is PSA / Ford sourced. Newer cars are 4 cylinder, the older D3 5 cylinder if i remember correctly? The V40 is quieter, more refined than the focus, the interior is a nice place to spend a journey so is well worth the extra cost, compared to the Ford. I have an older 1.6 D2, and at one point i wanted to drive it into a lake. Would I buy another? YES. But not with the PSA/ Ford engine
Before you choose diesel, think about how you use the car, unless you do decent mileage the petrol could be a sensible option