Congratulations! You'll love it. I bought a 9 inch harp machine 20 years ago, (Brother 1500) and FMQ many quilts on it, including queen size without any problems.
When I first got it a tip was shared with me that she was given by a Brother tech, to use stretch needles for FMQ, the longer grove for the thread helps prevent skipped stitches. The stretch needles made a huge difference. I don't know if this holds true for the Juki. I don't have one but have heard nothing but praise for Juki machines.