Thanks for the reply.
I received an answer from ASUS for a similar inquiry I made to them. In a nutshell, yes it is upgradable and also yes it is a rather involved process that requires almost complete disassembly of the casing. They do not recommend it as it would void the warranty.
They were professional enough to give me all necessary information but warned that proceeding would be at my risk.
I don't think I want to tackle such a complicated procedure and may defer to a pro shop.