The engine on the 2011 Forester reportedly has a timing chain, rather than the timing belt that has been used on Subaru 4-cylinder engines for decades. IMHO, avoiding a timing belt is a VERY good idea, so I would suggest going for the 2011 model, as long as you can verify that it has a timing chain, rather than a timing belt.
Subaru specifies replacement of the timing belt at 105 months, or 105k miles–whichever comes first.
By comparison, most cars with timing chains will run for well over 250k miles with no timing chain problems. Ergo–much less maintenance cost on a car with a timing chain. The new synthetic oil requirement is likely keyed to the new timing chain engine redesign.