Peltex is pricey, but if the pattern calls for it, you should use it as the particular bag you are making might need that stiff look, like a framed clutch bag. When the bag is done, it can stand up alone, no sag and the exterior is stiff. With fusible fleece, you get a soft look, stands alone, but has a sag to it. Like a sling bag. Some of my patterns call for canvas instead of Peltex, which is cheaper. Experiment what you like best and what gives you the best result for the type of bag you are making. I make lots of bags, and I learn something new everyday, especially from this board.