P.s. What your friend may be referring to when they said you have to "push a button to get into RNAV-1 mode", is manually altering the RNP if the route isn't correctly coded in the database (which shouldn't be the case). So if you're on an RNAV-1 route and the aircraft is flying at RNAV-5, it's a couple of button pushes in the FMC to change the nav tolerance to 1.0. Which as I stated before, won't actually affect or increase nav performance, only tolerance.