The only reason to add a quilting machine would be for the additional harp space. This is assuming you like your Viking for all other sewing tasks. Most of the dedicated quilting machines have just a straight-stitch but do it very well. You would still need the decorative stitches and buttonholes that you have on your current machine unless you strictly do quilting and nothing more. I know some of the new models do offer wide harp and a lot of stitches too but I also notice many of those (new) have been trouble-prone. I have an Elna that is like the Janome 6600 and it has the other features, but no free-arm. I think an ss only model + nicely loaded machine is a good solution IF you do many large quilts. Your Viking can probably do fine with up to lap-size.