I have a Sweet 16 sitdown setup, and I love it! I live very close to a long arm manufacturer, and they were kind enough to let me play with their frame setups for over an hour one day. While they were very helpful, it was enough to let me decide I really didn't want a frame setup at all. I have discovered I enjoy touching the fabric while I quilt, and I prefer a sitdown system. The Sweet 16 is a good compromise; it gives me a large enough throat to easily do free motion quilting and yet doesn't take too much space.
I bought mine at a local shop, and they service it. Since it is almost entirely mechanical (only the speed control and screen are electronic), they are pretty easy to service. Of course I haven't needed any service, but it's there if I ever do need it. I prefer a machine I can do most of the service on, and I can do this. The HQ folks give good support over the phone too.
Pam