My only argument against rating guilds based on total damage is my guild for example. Right now the strongest players in my guild have already earned their 7* Han Solo, so they're holding back and letting those of us who can put out 1.5-3m in damage take the top 15 spots on order to earn our Han Solo faster. Feasibly, our top 10-15 players are capable of doing 5-10m damage in heroic Rancor, but are being respectful of their less powerful guild mates. In reality, we don't care about the leader boards, but this change might end up causing more of the same cutthroat competition that we've sought to eliminate. Power players may abandon their diverse guilds in favor of the most powerful guilds. Just a thought.
Overall I like the ideas set forth for eliminating guild hopping.