On my domestic machine, I use Aurifil 50wt 2-ply cotton for both piecing and quilting. It is a fine, smooth thread that does not stiffen the quilt.
On my midarm frame setup, I use Glide 60wt polyester thread (my midarm doesn't do well with the Aurifil; not quite strong enough). Compared to the Aurifil, Glide has a slight sheen.
Both of these threads can be used for quilting 2" apart and not stiffen the quilt at all.
I hear you about the weight. That is another reason why I like the MM Blue Ribbon; I can actually carry the quilt without risking my back!
Just be aware that the MM BR is not needlepunched, so it does not have the stability of Quilter's Dream cotton (which is needlepunched and therefore can be quilted farther apart without risk of the batting coming apart) or Warm and Natural (which is needlepunched through scrim; scrim makes a batting even more stable, but also adds stiffness). MM BR simply has a bonding agent applied to the cotton to help keep it together while you are working with it. Handle gently, because it can pull apart. Some quilters complain about it being uneven, but any uneveness has not affected any of my quilts, and too thin -- but that's why antique quilts are so soft.
I had an opportunity to examine a baby quilt about 20 years after I had made it with MM BR. It had been through the washer/dryer many times and held up beautifully. What was extraordinary about it was the softness of the quilt. It looked and felt like a much-loved vintage quilt.