Been doing/changing of the two top boxes I have that fit on my 2019 XTown 300I ABS.
First GIVI E-46---carries a lot, dog likes, box heavy, because of size puts a lot of weight above and behind rear axle----can feel it there, so there is decrease in handling.
Second Bestem small box I got for $40, light, does not stick out so much on sides, dog likes, mounts a little more forward than GIVI, doesn't seem to hurt handling.
So in the interest of handling/feel Bestem will stay on.
Both boxes can be made to fit using the 4 pre tapped threads in rear wing. GIVI bolted direct, Bestem has light adapter plate, holes drilled in plate to match those in wing....this allows on/off of box....but I use security bolt with wing nut....as I do not want to lose dog or box
Any box/weight behind and above rear axle center is like adding rock to rear of arrow in my world....lighter/smaller the better.