I have a four-thread Singer serger and Singer 2001 sewing machine, both bought in 1975, so I am not much help. My Singers have had one heck of a workout over these years, as I've sewn jillians of garments and things.

BUT...though I can roll edges beautifully with mine, I wish I had a new one that does flat hem stitching. That's what I would get, if I were you.

You may be surprised how often you may use the serger, finishing seams for clothing they are wonderful.

I have 3 sergers, 2 are 5 thread (a coverhem on the one 5 thread) and a 4 thread.

Do a google on "Serger Reviews" see which one will fit your needs.

Thanks. I will check the reviews..