The Jazz II is .3” shorter than the 9” machine. To me, that is negligible to get 3 “ more width for the same price. The 9” has an automatic thread cutter that the Jazz doesn’t have. They both have needle down.
You should know the history of the Jazz II. When the original came out, it got a lot of attention because of its large harp with an affordable price. Quite a few people bought one, then realized they didn’t like to quilt without needle down. So after all the hype, it flopped without needle down. This Jazz II seams to be Babylock way of saving the original by adding the needle down.
In your shoes, I would get the Jazz II. But I have already shown I will gamble on an online machine purchase. I got my long arm online, untested, and I’m perfectly happy with my choice.