EA1FAQ (1249km) has been consistently spotting my 10m WSPR strongly, even though well outside of the main Es season and my little WSPR beacon runs just 500mW to a very average, low, wire antenna. Virtually every day I am spotted by someone. I assume this is Es. Backscatter is unlikely and the distance too short for F2.
I shall soon be moving over to JT65 on 10m only.