I know one thing,with a fact based rating as you call it you will greatly improve your trifecta strike rate if you rule out races where the facts are not as clear cut.

Leaving out maidens,2 and 3yo races will perhaps reduce your bets by a third but leave you with a higher strike rate and more chance of profit in your other races.

From that point a study of field size should show certain field sizes ie the larger ones to be more profitable.