True in a sense, but requires some clarification. First if you only change it to Metric you are not changing the default unit. A unit will still be what it is. And internally it is 1M in Blender both ways. So it is not the same as a unit in UE4. Because when you change it to 1 Meter the 1 is now 1 Meter. But if you leave it to 1 Unit and export you still have the same thing as if you set it to 1 Meter. And a meter or unit will come across as 1CM in Maya or UE.
If you set the scale in Blender to .01 and then export with the export scale set to 1 then you are in effect scaling up the Blender unit by 100. It is just a tricky way around the same thing. Which makes it arbitrary. And again confirms the 100 x disparity between Blender and UE4 if you are counting a default unit as 1 Meter without changing the scale as well.
It is easy to test what a unit is in UE 4 and it is clearly 1CM the same as Maya. As a 1CM cube in Maya is in fact 1 Unit in UE.
This fact is confirmed by a EG staff:
“The reason for the grid change is everything in UE4 is based off of Centimeters instead of Unreal Units. The metric system is divisible by 10, so it works in conjunction with our Base-10 math system very well.”
But all semantic and mathematical arguments aside it is like this:
Assuming there is an arbitrary Unit for all programs and we will call Maya and UE the center of the universe is 1.
Maya UE, (And Max by default I believe) = 1
Blender .01
Lightwave .01
Softimage .1
Those are the only ones I know.
The rest are similar I am sure.
So in short when sending stuff from Blender, one way or another scale it up by 100.
Softimage by 10
When working in Maya make sure you are using real world units. It can trick you as the default grid is real small. HIK rigs and characters from MotionBuilder are all in the proper scale for Maya and UE.