I have a Juki TL98Q that I LOVE for FMQ as well as piecing. The throat space on this one is around 9 inches, I believe, and I've done several queen-sized quilts on it. There is a picture of it on a queen-size that I recently finished here:
http://www.quiltingboard.com/t-162730-1.htm
There's a newer model out now, but basically the same machine. I love the thread cutter and use it constantly when piecing. This machine only does a straight stitch, and does it VERY well!