Don't hear of LBZ owners listing OH as a problem. One of the changes from LLY to LBZ was a larger radiator. Have 3 questions if the #1 is true.
1. Can LBZ Rad be used in LLY? NO, not in any practical sense
...3. Can someone compare of cooling capacity of LBZ & LLYability?
I can speculate an answer. The new rad is basically the same, only bigger, about 10-20% larger. The new fan appears to be able to be able to carry away 20% more air. So fan ops appear to be able to create a 10-20% increase in rejection performance, from around 500,000 BTU/hr (early LLY) to 600,000 (LBZ).
IMO, it does not appear that no-fan ops have been improved at all. The aerodynamics, and hence kinetic air throughput, will be the same, more or less.
So IMO, the parasitic cooling is better. The (free) cooling remains unimproved. The fan will be ( and according to reports, is) just as frequent and temporally nerve deadening. Just less chance of coolant on the ground.
My assessment based on a few hundred hours of research and testing.
opcorn: GM missed the smartest (and cheapest) thing they could have done. An aero mod to the nose.