Just my opinion, but beware of overestimating the warmth of two layers of 3-oz. Primaloft.
I have a Mountain Hardware Compressor Jacket, which uses Primaloft One (comparable to the Spruce), and it's not nearly as warm as a fairly light down jacket. Your experience has obviously been different from mine, though.
I don't mean to insult your intelligence here, but be sure and test your quilt under cold conditions before taking it to Rainier or Denali.
Also, the B46 nylon thread is kind of heavy for that light fabric. Regular Gutermann polyester thread will likely sew better.