You have the exact (pun intended) same situation at present.
Exacts can weigh between 8.3 grains and 8.7 grains within the same tin. That means they could run between 806 and 788, a difference of 18 FPS and both under the 12FPE.
Given that the chrono will not be spot on and neither would the scales you are always going to have a variance anyway.
I don't think anyone, FT or HFT would try to cheat the chrono. Peer pressure would soon stop it because that person would become "known".
Will be interesting to see how these pellets perform. If they can get the weight tolerance tight then they can start work on the size