Both SQ & UA 744s are using Pratt & Whitney engines but most of the old CX 747-467s are using Rolls Royce engines which has less performance.

However, in the recent years that CX had bought some of the SQ 747-412s as a second hand aircraft & mostly deploy them to the U.S. so if you are luckily on board one of them, you will have less chance to facing the re-fueling stop.

Here are the existing CX 744 fleet for your reference:

B-HOO 747-467 - 23814 / 705
B-HOP 747-467 - 23815 / 728
B-HOR 747-467 - 24631 / 771
B-HOS 747-467 - 24850 / 788
B-HOT 747-467 - 24851 / 813
B-HOV 747-467 - 25082 / 849
B-HOW 747-467 - 25211 / 873
B-HOX 747-467 - 24955 / 877
B-HOY 747-467 - 25351 / 887
B-HUA 747-467 - 25872 / 930
B-HUB 747-467 - 25873 / 937
B-HUD 747-467 - 25874 / 949
B-HUE 747-467 - 27117 / 970 **Named 'Stewart M John' on delivery**
B-HUF 747-467 - 25869 / 993
B-HUG 747-467 -25870 / 1007
B-HUI 747-467 - 27230 / 1033
B-HUJ 747-467 - 27595 / 1061
B-HKD 747-412 - 26548 / 923 ex 9V-SMN
B-HKE 747-412 - 25127 / 859 ex 9V-SMK
B-HKF 747-412 - 25128 / 860 ex 9V-SML
B-HKT 747-412 - 27132 / 955 ex 9V-SMQ
B-HKU 747-412 - 27069 / 1010 ex 9V-SMV
B-HKV 747-412 - 26552 / 1056 ex 9V-SPD

For further CX fleet details, you can also take a look at this site:
http://flyerguide.com/wiki/index.php/Fleet_Info_%28CX%29