Hi try this place for Legacy only advice.
I ran a 58 plate REN 2.0d for 3 years without issue, it did have a clutch judder from time to time ( which is a software fix according my mechanic, he was a Subaru technician)
Its a known fault that the cranks fail on the early ones, mine was one of the earliest and like I say was ok but I didn't welly it everywhere.
They can also pink, mine never did, think I was lucky.
Its best to seek as later one as you can, after 2010 I believe is ok, again look in the UK Legacy forum.
Mine achieved 45 to 50 mpg , smooth, quiet and being the REN had all the toys.
The engine prefers you to use the low down torque, revving it high serves no benefit as all the power is low down.
Bluetooth is not very good so I had a parrot fitted, satnavs a bit pessimistic, but overall a fantastic car.
Drove it in all weathers, towed a few supposed 4x4s out when we had that freak snow storm in 2010, loved it and only got rid as it was a company car on a PCP.
I've since had 3 GTBS, 1 Outback, a 3.0 spec B and now a JDM twinscroll, I cannot see me buying another brand or model.
I am already eyeing up the JDM Dit cars that are now available from Japan.
There are some people on the UK Legacy forum that live up near you too.
Hope that helps