Been reading up on 3 thread sergers.
Seems it is fairly well suited to the uses we will have for it.
The 4 thread sergers seem to be better suited for clothing seams as well as edging.
We'll be primarily edge binding stuff, for which a 3 thread seems perfectly acceptable. In some instances preferred.
I could have gotten a 4 or 5 thread, but that would have been mega bucks and probably have ended up being unused capacity/features.
My 20 buck unit should "fit the bill" very nicely for us.
Did I mention it was only 20 bucks?
I also just picked up a Singer service manual for it. We're all set to go.