So far I haven’t noticed an issue with the scaling of objects. However you might be correct as I am just using both engines as renderers for my art, and there may be issues I’ve yet to encounter related to gameplay.
As long as the meshes you reimport into UE4 are of the exact same size they were in UDK. The tool places them in the correct location, rotation, and scale.
However if there are issues related to the scaling, I could make the tool modify the values to fix them. For example I’m already having to convert the rotations. It wasn’t a simple copy/paste of the values in the right place because
UDK stored rotations in it’s own unit format (where 65536 was 360 degrees), my tool converts the value into normal degree rotations which is what UE4 is using.
I just tested that if you parent every mesh that got ported over, and change the parent’s scale. It re sizes everything correctly. That’s how you can fix any scale issues.