One of the interesting things is that the machines on frames only do straight stitches ... this Bernina has a whole host of cool stitches, which you wouldn't ever use if it's on the frame. Looking at the features of this system, I do like that it comes with the quilting design software, and it has a larger bobbin - both great features.
I started with a Pfaff GrandQuilter on my frame, which is a fine machine, but I was very quickly frustrated by the limitations of having only a wee area to quilt - which disappears quickly as you roll and progress from the top to the bottom - by the time I got to the bottom of the quilt, would have only five inches of area to quilt.
Truly, the best advice is to try out this setup, and as many other systems as you can get your hands on!