JohnG,
Yeah, on the first reading that CC article mystified me too, but what I think the contributors were saying was that:
The original 2 litre diesel engine was down on power and torque compared to expectation - certainly 110+ bhp from a 2 litre turbo diesel is uncompetitive when most diesel cars are offering 150+ bhp and vastly higher torque from a similar engine
The 2.5 litre petrol was more powerful and offered a similar level of torque, but sucked fuel.
Hence the (unusual) preference for the 2.5 litre petrol version.
They made no comment on the newer (Renault sourced) 136 bhp 2.2 litre diesel engine - which would seem to be the ideal version.
Robert