Thanks for finding the research DogHouseMom......that was my thought but to have it in writing from a group like AQS makes it easier to understand.
I can tell you that there is a huge difference (in many different ways) between moving the machine vs moving the fabric regardless of how big the harp is. I just finished a kingsized quilt on my HQsitdown and it felt like I was quilting a smaller quilt on my DSM! I've done both and pretty much it's the same movement and skill.