One problem with the portable machines, even with the "quilting table extension" is that the weight of the fabric pulls against you sewing a straight line.
With a flush to the table set up, the fabric is supported by the table and you can more easily slide the fabric rather than pull it through the machine.
I love my Brother CS6000i, but it needs to be repaired from so much "pulling"by the weight of the fabric to the left and back, toward my lap. The needle arm is actually curved now, instead of straight! I made just over 100 denim quilts, 3 Crazy Quilts and 5 Project Linus quilts in the 3 years that I've owned the Brother CS 6000i.
At $159. for a new one, I can't see spending $120. minimum to service/repair it.
I am back to the 1970s Singer Stylist that inherited from a neighbor.