as long as you measure your seam allowance and set the machine for that, or use a guide, you can use different machines!
It is more important to use the same ruler to cut out the entire quilt so that it always accurate.
and yes, 50wt or 60 wt known as bobbin thread does lie flatter...BUT so would use thinner fabric...which is NOT something I am going to do...unless you are making a block with many points going to together in one spot like a mariner compass, then it is not really necessary to worry about thread adding thickness to your seams...the thinner thread is important in paper pieces, as it allows the paper to be removed easier and in most pp'ing projects you do have many points/seams coming together so the thinner thread would be best!
Hope all that made sense!