I like your calculations. In most parts I totally agree and like the nw system for myself aswell. It feels more rewarding.
About the the gold/dust calculations in the new system I got a slighly improvement:
I would not add all the early rewards to the calculations. For example: the packs from older expansions are not worth 100g, they are for most people outdated and max worth 60-80% than packs from the latest expansion. The free given legandary does not count aswell, because blizzard gave a free legendary for all players in the past aswell.
This makes your calculations a bit worse for the new system.
I like your efford and appreciate that work. Thanks.