I had that air-threading BabyLock on my wish list, but jeepers, if the air mechanism breaks, how do you thread your serger?
I have a really low-end Brother (which I think was manufactured by the same company as BabyLock) that I absolutely love. I can almost thread it with my eyes closed - the first two sergers I had were enough to make you pull your hair out. So frustrating! And if you didn't get it set exactly right, the dern thread would break - you'd have to start all over. This one is a piece 'a cake.
Converting to the rolled hem stitch and back takes five seconds. It's more difficult to convert to the coverstitch look - but I've read that you do better to buy a machine made to do coverstitch if you want to make a lot of t-shirt-type things.
I trim and serge the edges of my quilts when they're quilted and ready for the borders or binding to be applied. Such a nice edge and a good guideline for sewing on the next step.
I made a whole quilt top on the serger once - it was a lot of fun and since it was for a toddler, I bet it will last a long time. The back of that quilt was so neat and clean that I thought about maybe doing another top with colored threads so that all the serging shows on top. That could be pretty.
If I ever manage to buy the air-threaded serger, I would still keep this one around as a backup. Have fun shopping and I hope you find the new toy that works just right for you.