I use Max with Unreal and Unity. For a long time I worked with the System Units set to 1 unit = 1 cm, but displaying generic units. Now I switched over to displaying in cm just cause I like it as a reminder. Also it was very embarrassing when I realized years down the road that Max will automatically convert any unit you…
I tend to use cm for personal work and decimetres for work stuff - 1/10th scale seems work work well for capital ship size objects. 800 metres in-engine is excessive, 80 is doable.