"the next one will be 100% sewn edges"
It would be easy to take your quilt and sew around the edges
"....is primaloft sport easier?"
I have used a number of different insulations and they are all similarly a bit of a pain to work with.
But so what, it's a bit of a pain, just manage it. Like do all the sewing you can before working with the insulation, which is your "envelope method". Think about any straps or anything, whether it would be easier to do before ot after adding the insulation.