I have a Grace Z44 quilting frame that I bought several years ago when I first started quilting. Mine has the wooden cogs whereas I think the newer ones are made from a different material. Also I have the wooden bars. I have used the frame more for basting than for actual quilting only because I could never master quilting backwards with my thumb. I was so slow that I gave up and did my quilting on either my lap hoop or my Grace floor hoop. I have given much thought recently, however, to try using the floor frame again. Perhaps being a little more seasoned to hand quilting I might have the patience to try thumb quilting again. I am quilting a cross hatch grid now on my floor hoop (using masking tape as marker) and I'm having a hard time keeping the lines straight (have ripped out almost as many stitches as I have put in, but that's another story). I'm thinking that on the frame the long lines would be easier to see and keep straight, not to mention that you can see what you have quilted without spreading it on the floor. Even though I haven't quilted a whole quilt on the frame I would still recommend the Grace Z44. If you are comfortable quilting in all directions and have the room, then go for it. I like the floor hoop for smaller quilts; however, the quilt I'm quilting on it now is 90 x 90 and it works fine. The nice part about the floor hoop is that I can sit in my comfortable chair in the living room and the bottom of the frame slides under my chair and I can stitch away for long periods of time. If you do get the floor frame be sure you have a comfortable chair on rollers. The Grace frame can also be adjusted to your comfortable spot. I have never used the hoop that you sit on, but it ought to work fine. The only downside to it that I can think of would be that it might be cumbersome getting up from your chair. My lap hoop is only a hoop bjt I can just wrap the quilt around the hoop and go. Having said that I leave the hoop in only when I'm stretching for a few minutes. If I'm not going to be quilting for a while, I remove the quilt from the hoop.
Hope this helps you with your decision. Let me know what you decide.