I enjoy piecing quilts more than quilting them. I make a lot and give just about all of them away. I had to find an economical way of getting my quilts quilted. I have the BlockRockit on a Grace GMQ Pro frame. I was using a Janome 1600P and didn't have enough space under the throat. Also, my quilting wasn't smooth. I had squares or ovals instead of circles. My quilting space was limited to about 4 inches when I got to the bottom. I now have about 10in. of space at the bottom of my quilt. The sewing is so smooth that I have started doing FMQ on the frame. I was relunctant to do this before due to lack of confidence. Since the Qnique and the BlockRockit are the same machine, I suggest you talk to Lynn of KathyQuilts.com. He is at the Lancaster Quilt Show this week with the machine. He developed the machine along with Grace and they both sell it and support it. You will get a lot of help from Lynn via phone and email and the BlockRockit yahoo group. Lynn explains the difference in buying from KathyQuilts and Grace is: KathyQuilts is run by quilters while Grace is a manufactorer with technological knowledge. Both will support you but the knowledge base is different.
Now, about the frames. There are some members who change the size of their quilt frame. However, it isn't a quick or easy job or something I would want to do often. Most members on the forum put furniture sliders under their frame and slide it against a wall when not in use. There are different size frames available. You may want to consider buying a smaller frame if you only make small quilts. If you buy a frame that will quilt a particular size, be aware that if you want to quilt something bigger, you will not be able to do so. I hope I answered some of your questions.