I'm working on a quilt right now that is quite complex. I'm to a point where I'm starting something new that I've never tried before ( curved piecing) and I keep putting off. Now , after quilting 11 years I KNOW that the fear of doing it will be way worse than jumping right in. I just need to clear that "fear" hurdle. My guess is that it's the same for you.
I would guess that if you do have a problem then someone here on this site can help you with that exact kit. It's stunning quilt and will be worth the effort.
I've made several of Jinny's quilt kits and also hand pieced a wallhanging of hers. Truth be told, I bought the perfect piecer but have yet to use it. So no, it's not necessary. If Moonglow is almost all paperpieced ( as I suspect) the perfect piecer won't help much.