Depends on how we’re defining “heavy” right now. They’ve gotten more percussive and articulate over time, from Rev 1/2 -> Blue -> UU for example, with the oldest ones being the “loosest” as people would say and the most recent being the “tightest” and more articulate, but the older ones sound “bigger” IMO. Depends on your definition of heavy, and as mentioned earlier, no two are ever the same.
What’s funny is the cult following the of the oldest ones (Rev 1/2) tend to fall in line with the people that also want Recto Rev Cs and etc. But, the reason folks allege to like the Cs should be the reason they like later versions of the Uber better, but it’s not the case.
Makes me think what people really like is the oldest and hardest to find versions which everyone has convinced themselves are the “best,” whether it’s Rectos, Ubers, 5150s, Soldanos, Diezels, etc.