Subaru Repair: Subaru engine life, double overhead cam, coolant leak

Question
on the late model 2.5,  say 98-01, with proper maintenance, what is the life expectancy of the engine?

Answer
98 and many 99's are DOHC engines. Some 99's and almost all 00 and 01's are SOHC engines. The double overhead cam engines seem to have more oil leaks, noises, and head gasket issues. The single overhead engines don't have the engine noise or oil leak problems, but still have some external coolant leak issues at the head gaskets. If I could choose, I would take the SOHC engine over the DOHC. And for the record, I have seen both go over 300,000 miles.