You might appreciate the extra torque the CB500X has to offer on the highway. Not a whole lot more HP, probably good for 190 km/h indicated max speed vs. 170 km/h, but almost double the torque. You can cruise at 130 on the Versys-X 300 with a bit of downshifting up the bigger hills while you may not have to downshift at all on the 500.
If you're mostly planning to do off-roading, the Versys-X 300 which is 45 lb less will be appreciated.