I have been a using Nxstage products for 4 plus years now. Their products have gotten a lot worse. I lose almost half my supplies every delivery due to defects in the sacks that make the solution, prime packs that get used twice as fast now because instead of getting two treatments to a sack you only get one because of defects. Unless Nxstage starts addressing these issues seriously they will lose a lot more money than they could ever think about making.
I to have been using the NxStage PureFlow since July 2006 and never had a defective Sak. We are currently on a 20 liter therapy which provides a full 3 tx capability. What is the nature of the sak defect you are experiencing.