BA/QF compared to CX lounges in SIN are, like you said, quite a far distance from each other. I vaguely remember the CX lounge having a few more hot food options from BA though. When the BA/QF flights are close to leaving, it becomes very crowded in the BA/QF lounge. So crowded that there are lines, not just a waitlist, but a real line for the shower. Apparently people didn't like the way the shower list was being kept. I kind of remember First passengers getting priority....but how many people standing in line would let a First passenger butt in line to get a shower? I wouldn't even try it. You could get seriously hurt.

I have only used those lounges a few times though so this may not be very indicitive of how things typically are.