I have the 6600 and the 8900. THe 6600 worked pretty well but was quite picky for me on thread. Also, I had a terrible time fmq'ing on it. I can FMQ much easier on the 8900 and it's not as picky. Neither machine likes very bulky seams. Between the 2 machines, I definitely prefer the 8900. I bought the 6600 5 years for about $1600. I paid $2500 for the 8900 in Jan. It was a little used floor model. Hope that helps.