I have had the 2000ATS for several years with no problems. I checked the website and description for 2900 has several improvements over mine. I only used it for 3 & 4 thread overlock. To change to rolled hem was too fussy for me. Take some scraps with you and try it out. Also, check over at Pattern Review. What do wish to do with a serger? I recently treated myself to a Babylock Evolve. It is a pleasure to use.
Mary Ellen