As I will have few non-US transactions before the end of the year, it seems a good time for an update:
Chase IHG MC vs XE: -.17%
SPG Amex vs XE: +0.30%
Chase MP Visa last half 2015 vs XE: +0.88%
Using only paired same-day transactions:
SPG Amex vs IHG MC: +.34%
MP Visa vs IHG MC: +1.06%