I have two Pfaff mechanical machines, a 262 and 130 that have 8" harps. I love them for FMQ on smaller projects. I have a Pfaff 2170 with IDT, which is sooooo convenient to just pull that little lever down instead of switching out to a walking foot if doing SID. But the throat or harp is too small also for large projects and would love to have a Pfaff Quilt Expressions 4.0. I also have a Viking Diamond Deluxe which has a 10" throat and I did SID and FMQ a queen size quilt. However, with a touch screen in area to your right the bulk of the big quilt, if you aren't careful, will push onto the touch screen and change your settings and you may not know it. Otherwise, the FMQ on this machine is fabulous. I still would like to have a Pfaff QE 4.0 where the settings are up above and out of reach of the quilt bulk. I also would consider the Viking Sapphire 875 because even though the settings are in same area as the Viking Diamond Deluxe they are not touch screen, but then the Viking does not have the convenient IDT which is a Pfaff trademark and quilters love. For SID on the Viking I do have the Walking Foot with the three interchangeable feet to attach to it which works great.
So I say, test drive, go home and think, test drive test drive test drive.