Hi, I can't answer your question re the Koga, but last year, and after much research I was going to get the Motus. (I wanted 500w Bosch mid drive, hub gears and belt drive). Problem was I ended up doing too much research and by the time I had procrastinated for so long they had sold out of the spec I wanted!
I ended up seeing a good deal on the Raleigh Centros for the same money so got that just before the Pandemic seemed to wipe out all the the stock availability. To date I have not been disappointed, a great ride with a good range (90 miles when ridden mainly in "ECO" mode which I find enough with the odd "power up" for hilly bits). Electric bikes are expensive for what they are and I don't really see what "extra" you are going to get by paying more than double your current budget? ......certainly not double the quality if they are using the same motor system?