I have a 6600 and recently bought the 7700. I love them both. The 7700 is not sensitive, it is a wonderful machine. They are NOT discontinued, NOT, NOT, NOT!! I wish people would stop with these tales. The red front has been changed to white, bit it is the same machine with a few less accessories.
The 7700 is in some ways very different from the 6600 and many people did not take the time to learn the new machine, they just complained about it, and blamed the machine when it was user error. MY first bobbin was a mess because I did not read the directions....MY fault. Feet from the 6600 work on the 7700.