I use L bobbins all the time in my Husqvarna Viking Designer SE. I use NEB bobbins (clear plastic sides) that I found at http://www.discountembroiderysupply.com

Prewound bobbins will not work in earlier Husqvarna models, like the #1+, but they work fine in the Designer SE.

Pre-wound bobbins are the great thing since the rotary cutter.
I love using them. Even the cheap ones from Wally world work on my Baby-lock.

Love them. My Babylock has an adapter to use with prewounds.

I use them in my Pfaff 7570 all the time. No problems. I was told that in this machine I should take the cardboard ends off, so that is what I do. Works great.

I have a ton of bobbins already wound. I also have a sidewinder, a gift I love, and I can't see getting prewounds but I guess my machine can't use them anyway.(Bernina virtuosa 153 QE). I can see the sense of using them for embroidery though.

My daughter has a commercial embroidery machine and uses prewound bobbins all the time because it saves so much time. I recently got some for my Babylock sewing/embroidery machine because it winds the bobbins oddly and they sometimes jam. So...until I can get it to the shop I will use the prewounds.

Taking one or both ends works on my Pfaff too. Buy them in cream and light grey and they last so much longer than when I wind bobbins myself. Have been able to use them with Clark and Mettler top threads without any problem. May in Jersey

I am confused to how and when you would use prewound bobbins because in most of my quilting projects I find, for tension reasons, that I need to have the same type of thread top and bottom. Are they just for embroidery?

I have no problem using them for regular sewing and quilting projects. I always do a trial run first to make use the tensions are OK. May in Jersey

Since the prewounds tend to be polyester, I would only use them for embroidery.