One of my customers went around town to the local bike shops asking about this.
The Sturmey Archer was not recommended for anything powered...The one guy said he had gone through 3 on a customer's electric bike.
He recommended the SRAM. He wasn't pushing inventory; the unit had to be ordered. My customer ordered one, and I took it apart. It appears to be well made. They are made in Germany, so I guess that alone speaks for the quality.
I'm using it, mounted to the frame, as a transmission for a Spoiler. We'll see if it holds up.
Jim