[Joel]

Fortunately for me for the last 2.5 years I've been part of the furniture at the local Suby specialist here, the owner is an old VW nut from way back and has a real interest in my car and conversion and has helped out heaps with it.
We've not long built up a new EJ25 for it.

Being there frequently I've seen alot of what goes on with these engines.
Aside from head gaskets the main issues coming in are caused by operator error rather than the engines fault.
The turbo engines are far more problematic, spun bearings is the most common one but it's more from how they are driven, you don't buy a turbo car to drive like a grandma.

As long as all the maintenance is adhered to they last very well.
nearly all the N/A engines with 300,000KM+ still have the cross hatching in the bores.
People not changing oil, coolant, filters, timing belts, water pumps at recommended intervals is what causes problems

and thats the same with any engine, I dealt with enough problem child Type 4 engines at the VW garage to last a lifetime but thats cos busses are driven hard and not maintained.