Starting a new thread since the previous one was from 2021, as per this thread it looks like we'll need to get a new HWC, in fact it's surprising the current one has held up so well.  It's a low-pressure Rheem 135L from 1984, the current thing to use seems to be mains-pressure, and since there's no plans to sell up at any point it'll be whatever's the longest-lived one.  From the Rheem warranty info that's either a SS (mains-pressure only so no choice there) or a VE.

Other info, the house is on a solar ESS so a lower-power element would be a good thing so it can heat gradually off solar only rather than draining the batteries, and hot water consumption is minimal, just short showers on a low-flow head and nothing else.  There's the option of flash heaters but they don't seem very compatible with an ESS because of their higher current draw when operating.

One other thing would be a thermostat pocket to drop a DS18B20 or similar to monitor things via HA, if I'm going to shell out thousands of dollars for a replacement I'd like to not be using century-old technology to handle the temperature.