An upper flipper shot into a dead-end target on the Pro.....that one is a head-scratcher.

Not a good comparison. There are two shots for the upper left flipper; one is a dead end target, you are correct, but right next to it is a repeatable looping shot. That same dead end target can be hit by both bottom flippers although not easily (left flipper directly, right flipper skipping off the extra ball stand-up). So it doesn't rely only on the upper left flipper to collect super jackpots. And all of that is in the context of IMDN also having an upper right flipper that has a repeatable loop shot as well. None of these shots change pro to premium.

On LZ Prem, what is a continued momentum safe return turns into a stop and dribble, out of control return for the exact same shot on the Pro. This one design element looks to be a deal breaker for the pro at least for me.

Typically the gameplay trade off is less mechs on the Pro, but with the benefit of faster play to the point some prefer Pros for the better shooting. It looks like for LZ, the Pro loses both mechs AND flow. I just don't get it.