The condo I just moved into has an original 2001 gas water heater that is missing a few features one would like to see in 2015, such as inspectable anodes. The home inspector pointed this out as a potential problem but only due to the heater's age; not due to any kind of malfunction.
Is this the kind of job where one should wait until the heater starts to malfunction? Is there a recommended replacement schedule one should use? Are newer models efficient enough that it makes sense to replace it anyway?