I have been moving my Amex to AA miles in family accounts.
There is a loophole in the system on points.com.
50k Aeroplan gets you 42k US but only 18k AA
Given that with the merger you can get 42k AA if you can wait a year, the obvious solution to it was to get Amex to US first to get 42k instead of 18k AA with each 50k Amex.

You lose 16% instead of 60% in the conversion.
(I know I should have moved my Amex when Aeroplan had a 30% bonus for Amex, then there would have been no loss).
You also do not pay 6% taxes on Amex when going to AP, so the real loss is about 10% at most when converting slowly to AA.

I ran into this problem recently; so this is just a FYI.
Yearly max move of 100000
back to trade, exchange & buy
Please review the information for the exchange you would like to accept, and then click continue to complete the transaction.
Do not move more than 100k Amex to Aeroplan in 1 account.
You can of course move 100k Amex to EACH aeroplan account and move them from there to each US = 84k each account.