Will going to higher btu water heaters in this situation waste gas?

[starfish11040]

I will increase the tank size on my two water heater system to meet the hot water needs of the tenants. I am also planning on going from 40,000 btu's to 65,000.
My concern is that if it turns out that this system's FHR is more than I need to meet the peak demand then I will be wasting gas. Will this high recovery be overkill and waste?