Is that true? I’ve got a heat pump water heater that’s 400% efficient versus direct heating would be somewhere less than 100%, no?

I think I read it ends up being close with solar heat still winning. The panels have a range of effectiveness and the heat pump isn't always 400%. The solar thermal is cheap too so even if efficiency were superior with PV panels it would still only be useful if you just had a massive excess of wattage.

Yes but. It turns out that PV solar wins on maintenance by a lot; since you don't have to run hot water pipes and keep the solar heater from leaking. With a reasonable system design you can pretty much just connect the wires to your heater element.