I love my 6600. I am so glad that I bought it.. it was worth every penny. I don't know what changed moving from the 6500 to the 6600... and I don't know how much money you want to spend either.... but if you have the $$ and are going to sew you won't be sorry if you buy the 6600. The only thing that I would change about the 6600 is the bed of the machine. I can't get sleeves or skinny pants over the bottom to sew on them. Some machines have a piece that pulls off to allow the smaller sleeves but this machine doesn't. Luckily I don't do much of that stuff
