Does your dealer have a machine that does embroidery and regular sewing? I've never heard of anyone using just an embroidery machine to quilt. You should be able to free motion quilt with your Janome 6600. I've done twin-size on a Janome 6500. Are there any shops in your area that let you rent time on a long-arm machine? That is what I have done for larger quilts. It really is much faster and easier than doing it on a regular sewing machine.