this is my 2 cents on the matter
gearscore is abused like hell in my eyes by the ppl looking for ppl and ppl who wants to join.
but gearscore is also broken sens it doesn't take in class and specc only ilvl gear.
i personaly don't use gearscore but it needs to get more complex, i think one thing is insted of simply saying gearscore based on ilvl i need to take the class and specc into the matter to say a more accurate gearscore take this as en example retri paladin trinkets the armor pen trinkets are useless for retri paladins but the trinket from FoS is ilvl232 and the greatness card is only 200 and that will make it look like the armor pen trinket is better when it is not. things like that is what need to change if gearscore is ever to be used to make a pug raid.
P.S how about a aichv score the more raiding aichvments you have done the higher you are. kinda like how some sites judge what the best guild is atm but person to person??