I find the higher loft batting a little more difficult to work with than lower lofts. Maybe buy a small amount and make a practice sandwich to see how you like it?
I have used low loft, and added extra pieces of cotton batting here and there to make certain elements puff up a bit more. Cut it approx 3/8" wider than the area you want to puff up. Quilt around the squares and then run a stitch like a serpentine or stippling around the edges of it to flatten down the edges a bit. :D:D:D