I've never notice, because I dont use grey potions, but i think its true....i dont remember grey potions only healing 20% of HP, but once again, im not sure.
With giants i believe nothing changed.
By the way...i stop playing this game for more than a year, and I recently started to play again. I've noticed the potions' recipes are different, because i dont remember using any ink. Is there anything where i can see the difference between the "old recipe" and the "new recipe"? Im just asking because I feel I am more independant from geologist/jeweller, but more dependant of fisherman/sorcerer.