I have a HQ Sweet 16 and currently using it to interline open areas of a cut work and white work linen table cloth with very fine batiste cotton before sandwiching up for quilting. (Lots of swirls and eyelet filled ribbons but some straight line areas). I am only doing this on the HQS16 because the cloth is too big to fit in my DSM.
Even though I am using a fine thread and needle, the stitch quality on the back isn’t as quite as good as my DSM on such fine material. It seems to me (although I may be wrong) the quality isn’t there because it isn’t sewing through a quilt sandwich, there are no feed dogs and this is not a "sewing machine".
A mid-arm takes up space, and takes money! I bought the HQS16 because I have the space; it was a treat to myself for a milestone birthday; I enjoy the quilting more than piecing and I already had a newish DSM that was small enough and light enough to take with me to workshops.
So lots to consider. Hope this helps.
HettyB