I sew a lot of knits and, honestly, should have purchased a coverstitch years ago. Most of the knits I sew can be done almost entirely with the serger and the coverstitch. The Janome Coverpro 1000 CPX works great for my needs. I must admit it did take a little practice. It does not sew quite as smoothly as a regular sewing machine. But maybe it is not supposed to. I wasn't able to test drive any coverstitch machines before I ordered the Janome from a local dealer who carries Janome machines, but no coverstitch machines, in stock. I based my decision on the information and support from the Janome Coverpro forum at Patternreview.com. I can't imagine any question that couldn't be answered on the Coverpro discussion group. They even suggest the best suppliers for needles and accessories. There are little tricks to be learned, such as how to end the stitching in the middle of the fabric, such as a sleeve hem, rather than sewing off the end of the fabric. There are great Janome tutorials for this on YouTube and I still refer to them if I haven't used the coverstitch for some time. Believe me, if you don't end the stitching correctly, your entire row of stitching ravels out!
As with any new machine, it takes practice and experimentation with the different fabrics. For example, I soon learned that, when hemming a lightweight knit, I needed to add a little support to the fabric so that the hem doesn't tunnel. I use Design Plus ultra-soft double sided fusible to fuse the hems in place and to prevent tunneling. I haven't tried other brands but I'm sure there are other options available as well.
This is an example of a sleeve hem on a very lightweight knit which I fused first with 3/8" double sided fusible. Not only does it prevent tunneling, it also helps me to press up a very even 3/8" hem. Since coverstitch hemming is done from the right side, it is important to work with an even hem.
For this medium weight jersey knit top, I was able to use the coverstitch machine to finish the neckline band, the sleeve hems and the bottom hem. I made a self-fabric binding and sewed it on with the regular machine first because, sometimes, I pull the binding a little too tight as I sew it on. I try to get it right with a long machine stitch before I serge or coverstitch so I can easily remove the stitching and sew it again until I get the look that I like. I have experimented with a row of stitching on each side of the seam as I coverstitch as seen in RTW, but decided that I have more control with this method.
This is the sleeve hem of the same top. I fused the hem with the double-sided fusible and sewed the hem before sewing the side seam. Since this is a medium weight knit, I could have sewn this hem without the fusible, however, I have found that it is much easier to coverstitch narrow hems with the fusible.
This is the bottom hem of the top. I sewed the front and back hems on the coverstitch before sewing the side seams and adding the ties. I didn't use the fusible on the bottom hem since this is a medium weight knit. It worked fine without it and did not tunnel.
Now for the fun stuff! I tried to find ribbing for this Kwik Sew 3090 knit baby gown at the local Hancock Fabrics. They don't carry it at all. I went next door to Rugged Wearhouse, an outlet type store, to search for a ribbed garment I could cut up and use for ribbing. I found Gap tank tops in the junior department for $1 each! That's a lot of ribbing for $1. I was able to remove the ribbing from the neck and both armholes and use it for this gown and bib. It was already the right size and pre-folded for me. I guess it doesn't take much to excite me because this find made my day! I still have the rest of the tank top to cut up and use for ribbing on other projects.
This little gown is made from two boys t-shirts I found on the clearance rack at WalMart, a stripe and a coordinating solid. I used the solid for the neck trim, sleeve band, and for the hat. The hat is Kwik Sew 2433.
For this type of binding, I sewed it on right sides together, stretching slightly. Then I pressed to the inside and pinned without turning under the edge. I sewed with the coverstitch and then trimmed close to the stitching. I notice this method used often in RTW knits when I do "snoop" shopping.
I like the elastic at the bottom which pulls in the gown a little to help keep baby's feet covered. I quartered the elastic and the gown bottom, pinned, and stitched with the regular machine before turning to the inside and final stitching with the coverstitch. I used two different colors of thread because I was too lazy to change the thread but I don't think baby will mind.
I made all these projects in just a few days using primarily the serger and coverstitch machine. I have sewn knits for as long as I can remember, but never with the professional results I enjoy with the coverstitch machine. It would have been great to try out several machines before purchasing but they just aren't available to me locally. I especially would have liked to try out a serger/coverstitch combination machine. However, it would have to be extremely fast to convert back and forth to make me happy.
Good luck with your search for the right coverstitch machine. I would still be sewing knits if I didn't have one but, as I mentioned earlier, I wish I had purchased one long before I did!