I have a huge spool of 50 wt, 100% Egyptian cotton thread that was recommended to me for FMQ. I've used it for that but still have lots of it. Would you use this for piecing a quilt top together?

Sure. That's how Connecting Threads advertises their thread.

I do and so far no problems, knock on wood.

As long as your machine agrees, go for it! Mine can be tempermental with some kinds of thread (like connecting threads brand). But she LOVES Aurifil, Wonderfil, Gutterman, YLI.

Yep, I use the same for quilting as well as piecing.

I use it for piecing and FMQ - works very well on my machines. (Viking Rose, Featherweight, and White Quilter)

As you wish! :-)

Should be fine but I would suggest the perfect 1/4" seam test with 3 strips
of fabric. You might need to adjust your needle position slightly to accommodate for the thickness.

easypeezy has good info!

I would use it for both :D:D:D