I have lots of friends who absolutely love monofiliment thread & use it all the time. Me, I hate the stuff and won't use it and here is why. The main reason is that no one knows how the monofiliment thread will act with your quilt over the long haul. I know I do NOT want to spend 300 hours hand appliquing a quilt only to have the thread wear away the seams as it rubs or worse, simply break like old fishing line does after enough time has gone by & leaving me to redo all that work. I also hate the way it feels. My quilts are usually lap or bed quilts so feel is very important to me. I know you can't iron it from the front or you can melt the thread, and since I love to iron (okay, press!) this just won't work for me. I hear it is also sensitive to being put in a warm/hot dryer.
I know it can cover up a multitude of sins but for me, the shortcut isn't worth the problems that can occur. And since I want my quilts to last for a long, long time, I'd rather just use a color that matches the piece I'm working on and switch out threads if necessary over using the monofiliment. JMO.