Fwiw I have a Stromer ST1 with a bit over 18K miles and have had no motor issues (rode in rain, snow and sleet). Due to wrist issues I’ve switched to a Cattrike, and at the time the factory E version was scarce locally so the dealer put in an aftermarket Ekit, I did need to replace a motor due to rain damage (cracked case). The factory kit is Bosch and I doubt I’d have had issues with it (my wife has a Haibike with a Bosch motor).

good luck.