The Evolve's designation was BLE8, which leads me to believe it was always an 8 thread. There is a Diana which is a 5 thread. That's about the price for a Diana.
I remember when the Imagine (I have one) came out and the Evolve came out at the same time. It was an 8 thread.
Just looked through the BL Manuals and the Evolve was an 8 thread.
http://babylock.com/downloads/manuals/