The battery is not "non replaceable" you will still be able to remove the battery and replace it when it dies. it just means dropping the motor to do so. its just not quickly replaceable is all. same with the SC Heckler SL. SC and YT chose to do an internal battery like specialized does. internal batteries are more involved to replace but not irreplaceable.That's fair, I have never ridden a fazua, and the only one I have seen in the wild seems to have lasted long. But there are some serious horror stories on this forum.
But my issues go beyond the reliability. Why are YT charging twice the price for the SN when it will have so much less power and range then the decoy? I know this isn't specific to YT.
I rode a 70Nm Shimano motor for 5 years with a 504wh battery. After 3-4 years and 10,000km, on a cold wet winter's day the battery would not last an hour in the top assistance mode. Considering these SL bikes have such small non replaceable batteries that are going to be cycled frequently, I think they will age very poorly.
I have had 2 YTs, but looks to me like they are coming out way too late to the party with this.