RDURES - from experience, AA has the most sophisticated Res system in the world. Its fare calculation is almost always perfect. And CX's CRS actually is the closest to SABRE as can be - in terms of calculating fares, and routings.

QF and BA have now adopted the AMADEUS system and I can say from personal experience, AMADEUS calculates fares which are at least 20% higher than SABRE. Don't know why. FINNAIR and IBERIA are also on the AMADEUS system. I am now sure what LAN CHILE and AER LINGUS use.