I bought the Expression 4.0 last September and it drove me crazy. It was the 4th Pfaff I purchased and I LOVE the older ones!! It would NOT FMQ without breaking thread, skipping stitches, and the tension was never right. Took it back to the store for the 4th time and told them to keep it. After much discussion I upgraded to the Creative 4.0 and had the same problems so in less than a month I took it back. The store gave me store credit for the Expression and my money back for the upgrade to the Creative. I have lost confidence in the newer Pfaffs but I absolutely LOVE the older ones. I still have one and would not get rid of it for anything but I will not buy a newer one. The store offered me the Smarter but it doesn't FMQ, the feed dogs don't drop and there's not a foot for that, just didn't like the features.
I bought a Janome 6600 and love it. It took some experimenting to adjust it to what works for me but I really like it and the throat is 9" wide, which is why I wanted the Expression 4.0 Pfaff.
Good luck to you.