I have this exact cabinet (here it's the
Horn 'Eclipse') and I LOVE it. When I bought mine I got a 'blank' insert for the top as well as one cut for my Janome. I use the blank as a light box by putting a couple of battery lights from the Pound shop (Dollar store, lol) on top of machine when in the down position.
I've since bought a longer arm Pfaff QE 4 and it almost fills the space, so I haven't bothered with another insert. I love having all my things to hand - I keep a small iron and pad on the right side so I don't have to move if I just want to do small jobs like piecing seams, binding etc.