Tankless boilers were first designed for steam, which operates at 215F. By setting the control to 180F/150F, you invest less heat in it so it cycles faster. You'll get much more hot water from it if it is set to turn off the burner at 210F and 180F low. You aren't saving yourself from scalds at 150F, so make sure there is a mixing valve to reduce water temperature to less than 120F by mixing in cold water. This will also give you more hot water from the tap as a mixture of hot and cold.
You can interpose a timer between the burner connections that make the burner come on for hot water; that is usually the blue wire on the 8124 control. That way, you can still have heat when needed. If you don't have an 8124 control, that is the one meant for a tankless coil boiler; having the right control helps.