Be careful with pre 2009 diesels, there is a well known issue with the first version of the boxer diesel engine, giving sudden and unexpected engine failure - crank oil feed issue, which was redesigned in vs2 boxer engines.
I considered a diesel Legacy before settling on something else due to the unknown with the fault.
Ive had several petrol scoobies before and love them, but just dont trust the early diesels - they used the same engine in Impreza, Legacy and Forester