I have my Birthday present early by a couple of weeks 
It is the Juki 644D. Its beautiful and a 4 thread. My current overlocker is a 3 thread Janome MyLock. But as a 3 thread isn't suitable for lycra, I'm trading up.
So I'm having fun with my new machine and it fulfils all my serging wants but hells bells it was a sod to thread or are all 4 thread overlocker's the same 