The Bernina tech told me it does save on the clutch wear. He recommends pre wound bobbins.

I have and use the Deluxe model, works great for me, works better than the winder on my Pfaff. I tried the cheaper one of the two and did return it as it didn't work with Pfaff.
If purchasing from JAF read the fine print on your coupon, many times the Simplicity is excluded
I consider it one of my better buys.

And this is why I love my Singer Touch 'n Sew! Just push the little lever to the side and you can fill a bobbin in place without having to unthread your machine. I think Singer must have patented this feature or surely all machines would have it. My oh so sophisticated computerized Brother that does everything but make coffee is a pain when it comes to filling a bobbin. Glad to hear about these devices because I've wondered about a stand alone bobbin winder since I got the Brother.

My Brother, Janome and Bernina have this feature.

I am not one to buy many 'toys'. But, I bought this during a huge sale and I LOVE IT. I use it all the time. When I know I am about to start projects (like a bunch of the fabric square wreaths), I will load a bunch of assorted colored bobbins and stack them with under the spools on my thread holder. With my quilts, I tend to piece with neutrals, so I always have extra spools. This lets me reload a bobbin without rethreading the machine. I know that seems like a little thing, but it makes me happy!

I used to use it a lot, but then I bought a new Pfaff and those bobbins won't fit on the Sidewinder. With my new machine I have to unthread the needle to fill a bobbin. With my old New Home machine I could fill a bobbin without using the thread on the spindle or unthreading the needle.

I have one but don't use anymore as the bobbins don't seem to wind tight. I just use my machine and wind 5 to 7 bobbins at once so I have them on hand. I use mainly white or light grey thread for my quilting.

I have a side winder. It is the pink one which winds Viking bobbins. I use it when I wind thread on the pre-wound bobbins that I've used==they don't work on the machine winders.

I use mine all the time.

I've had mine since I discovered them years ago. I love it! I bought it because the bobbin winder on my machine got lazy & stopped working. Can't live without it!