Of course much higher. In general an absolute number is nonsense. You could put 3 people with level 1 characters in Alkaizer's game and he's single-handedly finish a GR85 or GR90 on his wizard. Four wizards could more than easily do that; while some of them would occasionally die, the DPS would be insane. I don't think the question was meant to be taken literally, but if so, it's probably 10-15 tiers less (assuming the same level of fishing). Keep in mind DPS characters would then still use some group skills (e.g., wizards alternating Black Hole, using some defensive buffs like shield or bubble, and so on). People often forget that this GR120 wasn't a one shot but took a lot of attempts.
Overall, the discussion in the last few posts has gone so much off-topic that I wonder if people actually understood the significance of OPs post. For weeks and months, the meta was settled and everyone believed there was only one possible combination for high GRs. Now out of nowhere those guys went out of their way and did a lot of testing to prove everyone wrong and find a dent in everyone's belief that the "meta is settled". And the fact that the Crusader was one of the most important support classes in the first four seasons and everyone knew it provided the highest damage buff compared to all support classes in the game just adds to the fact that this is not something that they're the first to try. I have tried this myself and argued about this with other people, although everyone convinced me that the Crusader is dead for support. The happier I am to see this revelation.
Now, in all threads we currently have on this forum, come to the one thread that proves the meta wrong and complain about the meta completely baffles me. It's almost off-topic when it goes exactly 100% against what Chewingnom wrote himself here: "Remember that the metagame is never settled in stone and copy/paste builds from Rank 1 guys doesn't mean you are playing the best setup (Or the only viable setup). There are so many build-possibilities, so many group synergies that maybe nobody thought about yet, that you can't just say "If Rank 1 is playing this, it is the best build/setup, no matter what". No."
Therefore, once again: Thanks, Chewingnom, for proving everyone wrong and not only discovering this, but proving what I'm trying to say for ages - the meta is never settled, especially with only a handful of people in Diablo 3 actually willing to change. And to everyone complaining about the meta: This thread is testament that the meta is never settled. I've said this a million times, but never ever forget season 3. Four month everyone thought the DH was the #1 DPS class, until the real potential of the wizard was discovered - too late even to top the leaderboards. So stop complaining but go out and do what Chewingnom did and prove them all wrong.