Wichita water is hard, and a softener addresses that at the source rather than dealing with the consequences one appliance at a time. Scale in the water heater, clogged aerators and shower heads, spotting on glassware and stiffness in laundry all trace to the same cause.
Sizing depends on hardness and household water use, and an undersized unit regenerates constantly while an oversized one wastes salt. Getting that right is most of the job.
The economic case is straightforward here. Softened water extends water heater life measurably, and in Wichita the heater is usually the most expensive thing the hard water is quietly damaging.
Technician insight
Plumb the outside hose bibs and any irrigation ahead of the softener. There is no reason to soften water for the lawn and every reason not to pay for the salt.