I've got one in the bedroom. I would get one for the living room but the instructions say not to put it near gas appliances (and I have that gas water heater in a hall closet.)
I asked the water heater replacement guy your question about tuneing up the water heater, and he said "no" but if you flushed them about every 6 months it would substanially increase the life span of the water heater by reducing the sediment. Our current water heater was installed in 1987, so there's that.
Well, the chimney sweeps are here now. Can't get to blockage from the basement due to the bend in the liner; are now going uptop. Good thing the young kid is fearless, it's a good 40 feet off the ground, and the chimney extends 10-12(or more) feet above the roofline. I'm NOT going outside to look.