As you roll your quilt up into the throat of the machine you loose quilting area. The shorter the throat the shorter the quilting area you are able to do on each pass. You can see the difference in these 2 pictures. As you roll the finished part of the quilt up you loose space. There are a lot of people that do great quilting on the smaller machines.
Domestic machine
[ATTACH=CONFIG]220122[/ATTACH]
Larger Stretch
[ATTACH=CONFIG]220123[/ATTACH]