I have a Super Quilter ProFlex frame... and a Bailey - both are sitting unused. I need to remedy that and start working on it again...
But anyhoooo... About the Juki... you will need to turn your quilt to be able to quilt a really big quilt. I opted to go with the Bailey - it's not a whole lot more than a Juki and it's a very basic workhorse but it has a much longer throat. You might want to consider something like that - and the Bailey guy has a deal with a frame so you can get a little discount there I'm sure
I'm sure that most places that sell the frame machines have a combo for getting the frame as well.