I test drove the Janome 7700 and I hate to say it I was not as impressed with it as I wanted to be. I wanted to absolutely love it but even at full speed I wanted it to free motion faster. I have a Janome 4900qc and it's my main machine. It's a nice machine but it's got a smaller throat so I was looking for something to sit down to quilt with. For less money, I can get the Sunshine 16 table model
http://www.sunshine16.com/TakeIt.html and have a machine that is only for quilting although I really wanted to be able to have a walking foot for the times that I want to do things like bindings or straight stitching on quilts. That is my only hesitation for getting that machine. I want something that sews fast.
A friend of mine has the Juki 2010 and loves it. It is a straight stitch only machine but she can not say enough nice things about it. She loves hers. I'm also considering that one as well. I don't make really big quilts often but her stitch quality is awesome and it is fast at 1500 stitches per minute which for me is a great speed for free motion.. I just wish it had a longer throat. I want longer than 9 if at all possible. ;'(
I completely understand your situation that's for sure. If I were you, I'd go and try out all the machines you possibly can before you buy because once you buy it, that's it, you got it. Resale on a used machine is not that great...