My RST with Alfine 8 is over 12,000 miles of reliable service (90% commuting). Remember to back pedal while changing gears, am told this will extend the life. I change the cable once a year, when it gets the oil changed/dipped.
Using 150 watts as a datum and with a 42/18 set up, I think the Alfine is OK up to 7% gradient - 75kg rider plus 12 kg touring load. A 42/22 set up might get you up to 10%.