There is one major change that came with GTS from GT6 for the start of the race.
In 99% of the cases in GT6 you got the fastest start by flooring the accelerator and wait for the countdown to happen. If you do that in GTS you will spin and stand still and go nowhere or even spin out. For most of the cars you have to keep lower revs at the start and when the countdown runs out you have to feed it in gently. I think that is much closer to a "real" start compared to GT6. Guys who get it right just fly off the line. Guys who don't are slower and sometimes are a cause for incidents already. Adding a False Start Check is not more realistic. Nowhere in the real world is a driver penalized on the grid. If False Start Check went along with a time penalty (it should be easy to add in GTS) or drive through penalty (like in Project Cars 2) it would have been more realistic. Since we have penalties "OFF".... my argument is against False Start Check.