I believe you will accumulate bonus miles faster and with more partners on NWA than on UA, so even if it requires more miles to upgrade Intl on NWA, you will have them in your WP account to use because you will have accumulated more miles on NWA.

To answer your question about current rewards or benefits on NWA for Million Miler Status, presently the only benefit is a Congratulatory Gift and Brass Luggage Tag. There is talk about improving the program, but I don't know if and when changes will occur.

Also, you can find out your lifetime Credited flight Miles by asking an elite agent. I had over 3,000,000 program miles in my Worldperks account before I reached 1 Million credited flight miles, with 125% Plat Bonus Miles, ongoing promos, and EQM bonuses for certain fares you probably earn 3 times the credited flight miles, if you are active in a lot of promotions your ratio might be closer to 4 times credited flight miles, example 3-1 ratio 750,000 program miles would equal 250,000 credited flight miles.

RC