I have the GrandQuilter which is equivalent to the Juki and it is a machine that ONLY goes forward or backwards. If you are looking for JUST a quilting machine, then that is fine but if you ever need to do any zigzag or blanket stitch or anything other than forward or backward (and you will) then go with a regular machine.
Don't know anything about vintage. To me that is just another name for "old" but I mean no offense with that statement.
Both colleagues at work are Janome fans and I am in the process of ditching my new Pfaff for a Janome. I will have to pick Patrice's brain a bit because she has both models I am investigating.
I agree with whoever wrote that you should identify what you NEED to have and what you WANT to have. Then compare the features. Being unhappy with a sewing machine is not like a bad haircut - it won't grow out, it will just grow moew frustrating.