There are several machines that are the same. Tin Lizzie has a sit down machine and the George machine is used by a famous award winning quilter.
What I noticed is that with a sit down machine, your hands are in charge of the design and moving the fabric around. The long arm gives you a big space so your quilt is not as bunched up. It is wonderful for "art" work and David Taylor has some wonderful award winning designs quilted entirely with the HQ Sweet Sixteen.
They cannot be used with a stylus or laser on pantographs as can a stand up long arm. So it all depends on what type of quilting you are going to do.
Note that there are award winning quilters who all use a domestic sewing machine.