i feel you....avoiding shimano after 4 Motors till they make significant changes. Bought the last motor with my own money (out of warranty) and sold the bike. i think every motor will die at some point, but i had no luck with shimano ep8.
I´m a bit puzzled by your statement that the gain in height would only be the % of sag. For 10mm more travel it would be 10mm higher minus the % of sag so it sits 7-7,5mm higher in the front. Is my brain stuck? :)