Nice analysis. I will try to check some of the details myself if I find time later.

It makes sense that maximum rewards are obtained by splitting coins into an arbitrarily large number of UTXOs. However, of course you are right the more important quantity is how much you need to split in order to get e.g. 99% of rewards. I wonder if the whales are bothered by the fact that they'd need a huge number of UTXOs.