Do I need a serger with 2 thread stitches?
You can make a rolled hem and flatlock stitches with a 3/4 thread serger, but 2 thread capability is nice to have. Since you use only 2 threads, it is handy with delicate fabrics. There is one less thread to worry about and on some fabrics you flatlock will be flatter! A two thread serger also makes a nice overedge stitch for finishing an edge.