I actually ran into this as well.
Turns out that it can be fixed in unity during import, under the "Model" section uncheck "Use File Scale" and set "Scale factor" to "0.2"
Every time you import an object from asset forge, you'll have to do this. You can make a preset for this, which will make it a little easier.. but if you set it to default every other model you import from other sources will now be incorrectly scaled.
So.. it'd be really cool if we could just set a unit scale in Asset Forge (which gets saved in between sessions) when we export FBX then we wouldn't have to worry about importing it into other programs as much. Given that each FBX file has a "UnitScaleFactor", hopefully it wouldn't be too difficult to implement?