I have an Evolve Wave, 8 thread (only if you want 8 threads) It does serging, cover stitch and all kinds of other features.
The most important feature is the Air threading.....this was the reason I got frustrated years ago with the "other sergers". Babylock is the only company that has the automatic air threading. Just push a button and the air puts the thread into the levers for serging. A breeze! All dealers have free instruction. There are so many books, dvd's and internet instruction as well....if you need it. The Quick reference guide that comes with these machines tells you all of the settings and then you just serge.
I use mine to sew the edge of my quilts before binding.
Diana in TX