I had a similar choice recently.... I was debating between the Janome 15000 which is a sewing and embroidery machine and the Pfaff Powerquilter 16.0 which is a sit down mid/long arm quilting machine (same machine as the Tiara) As this was a major purchase (as will yours be) I spent quite some time looking into both. I then sat myself down and asked myself what I wanted from a machine. I already had a Janome 7700 for piecing and a Brother 4000D for embroidery, so I asked did I really need a larger sewing and embroidery machine. I then went to the Festival of Quilts at the NEC and played with both. I was a serious purchaser and both Janome and Pfaff were happy to spend quite some time explaining their machines to me.
My decision........ I went with the Pfaff..... after playing with both and spending a night thinking about it, I realised that the Horizon has a great harp for piecing and the Brother is a fantastic embroidery machine..... but even with the large throat on the Horizon I struggled quilting a large quilt..... decision made.
My Pfaff is fantastic and I love the space....now all I have to do is practice my free motion quilting.
I hope this was helpful and helps you to think about what you really need and aids your decision making.
Good luck and let us know what you decide.
Hugs
Caroline
These