I have a Pfaff Quilt Expressions 4.0 and love it.
Features I love: IDT, needle up/needle down, low bobbin alert, 200 plus decorative stitches, beautiful straight stitches, feed dogs drop, foot "hovers" in needle down position. Additional feet have all cost me under $30 each (have heard that some brands are much higher). I don't use the knee lift at this time as I have never tried it. I love the space for quilting.
What I don't like--mainly the service that I have locally. The dealer is sweet as can be, but not the best communicator and I'm not confident in her knowledge of the specific machines. I have heard that they can be picky about threads but I just experiment with needle types, tension and such and so far have had no problems.
I was a sitting duck and paid about $2500. I know that they have sold for about $1500 since but not sure of current price.
There are so many good options out there that it can make a shopper crazed, but sounds like you are doing your homework. At some point we all have to bite the bullet and make a decision and I think that most of us always have a little "buyers remorse" after buying. I just know what features I had to have and didn't waver on that, which were
needle up/needle down, IDT, feed dogs drop, plenty of
throat space for quilting and am happy with those features.
Good luck!