Although these days I am very dependent on help with antenna work because of my stroke, I very much hope I can try a better antenna on 472kHz WSPR this autumn and winter. I have been surprised how well the earth-electrode "antenna" works, but another 10dB ERP would be really worth trying. I have in mind a long-wire, which needs a support at the end of the bungalow. I also need a better earth system.
My homebrew transverter for 472kHz puts out about 12W. With a better antenna an ERP around 50-100mW should be possible. At the moment, my 472kHz ERP is around 5mW.