The CrossTrek has the 2.0L engine, and the verdict isn't in on that one - too few engines with higher kms on them.
Most of the 2.5L NA engines seem to need the gaskets done at about 200K - not many last much longer than that. In some ways it's worse, not better. The kid's Forester has had the driver's side HG leaking for about 100K now, but externally oil only, so it keeps on trucking. On the older SOHC 2.5s you could extend the life of the HG by frequently changing coolant and using the Subaru Coolant Conditioner - some sort of stop-leak that doesn't gum up the cooling system. I'm sure that's how her car is at 440K on the original gaskets.
The later 2.5s seem to have a better gasket in terms of original build, but there seems no way to extend it's life much past 200K. Friends of mine bought a 2009 Forester to replace their 2000, and they, like me, changed the coolant every other year and religiously used the conditioner and their 2000 model was on the original gaskets when sold. Their 2009 didn't make 200K despite frequent coolant and oil changes. $3000 plus shop fees, taxes, etc, and it was painful. They sold it afterwards.