Using heat pumps for hot water also necessitates storage cylinders, vs modern gas boilers which heat on demand and don't need a cylinder. You can argue about th

Using heat pumps for hot water also necessitates storage cylinders, vs modern gas boilers which heat on demand and don't need a cylinder. You can argue about the relative efficiency of this vs heating water on demand (depends a lot on how predictable your usage patterns are) but the space requirements, which may imply a need to remodel in an unsatisfactory way even if someone has the square feet to spare, are a real barrier.