If you cannot compete, you do not belong. Drop down a league or two if you want to play. If you are unable to play, it is because you should not be there in the first place. No matter what happens, the 'super' guilds will always outmuscle the weak guilds. Whether they get double, triple or quadruple attrition. Those guilds have the players that have the GBs and other buildings that have 'superfied' their combat stats. Your whole 'idea' does not do anything except hurt other players, who are in bigger guilds, which is what makes it such a poor suggestion.
You do realize that some of these 'super' guilds as you like to call it, can even have just 5 or 10 players in them ... and some of the more open guilds, that permit less experienced players in their guilds can have 40, 50 or even 80 players in it. This is why your idea is so poor - it does nothing to stop the upper echelon of players, and just punishes those who are in larger guilds - active or not.
So, again, if you are not able to compete - the problem is not Inno or the GbG system, so much as the problem is that you are advanced in a league that you obviously do not belong in.