here is my point of view about realistic scale :
as far as you only use TG2 and don't import anything in another app, it is "useless".
for example, try to do a macro pictures or even a close up with real scale... you are limited to 1 mm detail, right ? 0.001 is the ultimate limit (and TG2 hates this value)
but as for my self, for example if my grass is 10 m tall instead of something like 10 cm, the little rocks around it will be something like 3 m tall and that allow me to give them a lot of details because the scale is 3 so i can add a lot of PF or fake stones up to 0.001. Now if you work with 10 cm gras (scale 0.1) i would be very surprise if you can have the same detail because your smallest scale will still be 0.001.
I don't know if i made myself clear, it is hard to explain that in english for me...
i'll try to write it differently if what i said is not understandable