My wife has had two of those stands for years. Never used them. She's got a 5 thread Singer 14UXXXX Quantum jam-a-matic serger that she doesn't use that often, and it's got it's own cone mounts.
She's been using the Coats and Gutermann machine quilting thread on her quilts that come on the cardboard tubes. Those tubes just flop around on the spool pins so I've been drilling out the 3/8" dowel rod pieces for those.
Works really good. Keeps the big hole spools nice and straight.
We've also got some of the smaller cones that have a big hole on the bottom and a smaller hole on top. The thread on those is perfect for the felt bags I make but that plastic cone flops around something awful. So I made some adapters for that using the dowel rod and cut off rims of larger spools.
I order a lot of my stuff from Sew-Classic and they have spool pins for the Singers that use the tap in pin with holes in them for use when use the large cones with the stands. Well, according to their text that helps keep the tension consistent by following the same path you'd use with the standard thread spools.
But - what if your machine has a good spool pin? Sure not going to yank it out just to put one in with a hole, so I was yacking with my wife and had an epiphany. I headed down to the basement and in 10 minutes had the little adapter built. Tried it out and it works great.
I've not tried the big cones with just the stand, it's kind of like the adapter came first then I hunted up the thread to try it.
As for worrying about the strength of the thread, not at all. I've tried it in two of my Singer 66s, one electric and one treadle and it's not broken once. I also tried it in my HOTHER and it flowed through the the mechanism slick as a greased door nob. The singers have the horizontal bobbin set up which is a bit harder on the thread and it's tension, I had to adjust them both. The HOTHER has the vertical bobbin set up and it didn't need anything.
Now my wife wants me to make another one so she can use some of the bigger spools on the 319K.
Joe