So, our house was built in 1994 and has a combination of storage and convector electric heating.

Some spare cash which could be well spent on higher efficiency heating.

So, I hear about ‘German’ electric radiators which apparently use clay internally.

Any thoughts or guidance from the STW massive?

Trying to get info as well. There seems to be a lot of energy efficient electric heaters on the market at the mo.
I’m still not convinced.

They still use 1kW of electricity to generate 1kW of heat; all they supposedly do is allow you to control the heating/cooling cycle in a different way.

Daytime electricity is one of the most expensive ways to heat your space. Look for alternatives and insulate as much as possible before thinking of spending money on new heaters.

Your old heaters will be far better in a better insulated and draught proofed building.

The “so” at the start of your sentences is superfluous.
No idea regarding electric heating.

Dimplex Quantum seems to be an efficient version of current systems.