I have an Elna 624DSE serger (in addition to the sewing machine). It does 2-3-4 threads, rolled hem, etc.
I am very happy with it. It is easy to thread (compared to some other sergers I've seen), works great, comes with cards that tell you what settings to use for what stitches.
IMO, it's a pretty basic machine, good as a first serger if you never had one before.
Couple things that it does not have: no free arm, so stitching small things (like attaching the ribbing to DS's sweatshirts necks and sleeves) is a little tricky, but I manage just fine. Also, it does not have a cover stitch (only 5-thread machines can do it -- by cover stich I mean the stitching where you get two parallel lines on top, and serger-look on the bottom, usually used to hem strtetchy fabrics-- if you look on your T-shirt sleeves and bottom you'll see what I am talking about)
Someday, if money isn't an issue (ha!
), I would love to have a 2-3-4-5 thread serger that does it all. But That mighrt never happen... I don't know if this is helpfull. Ask if you have more questions....