I have a Sweet 16 with the stitch regulator and while I have not mastered the art of FMQ, this machine does make it easier. MSRP for the Sweet 16 with TrueStitch is $6400 or at least it was when I got mine. (Of course I did not pay MSRP) What I like is the small footprint. We don't have space for a regular longarm plus I cannot stand for any length of time. We ended up getting some IKEA cabinets on one side for extra storage and extra table space. Then DH attached a fold-up table from IKEA to the other side for extra space.
Are you aware that there is a Yahoo group for the HQ Sit Down Machine? You can get some great info there too.