Dybvad417,
Your 987cX Si will use the same software update file as the U.S. versions units. All International units use the same software update files as their U.S. counterparts. The current software version for all 987 units is the 4.180 software version. No worries about what has been added in between the 3.240 version you have now and the 4.180 version as all of the updates between these is contained in the latest available version. So once you update your unit with the current version it’s just like you went back and made every update in between.
In case anyone asks: downloading the software update will not allow a U.S. version unit to start displaying in multiple languages or the in the metric system format. That is programmed into a separate part of the memory when the unit is first built and is not user changeable (though many have tried).