I always thought I didn't need/want a serger but love it now. There are numerous techniques (ruffles, belt loops, wave stitch) and projects for the serger. I have the O*vation which air threads the machine. It doesn't matter the order of threading. The new T*riumph machine will even thread the needles for you.
http://babylock.com/sergers/understanding-sergers.asp
Good luck on your decision!