Z tower endstop offset in the Eeprom settings round off to the nearest number.
lost me there.

Have yet to mess with that kind of thing. No the the first clue where that lot is.

Given that it never actually probes anywhere but three points on the outer rim - i there actually any point in doing a topographical 'level' with so few points ?

First test corner piece came out perfect :-)
Strut is snug as a bug in a rug !