I solved part of my problem. I have good sound now.
rm /usr/local/games/planeshift/libs/libasound.so.2
rm /usr/local/games/planeshift/libs/libasound.so.2.0.0
Let the game use the system versions.
EDIT:
After a few hours of testing:
1. Still lots of random seg faults preceded by hundreds of lines like -- hit!beam!
2. Twice, the sounds just seemed to stop after a while, but this is unclear because both times as soon as I noticed that sounds weren't playing, I got a seg fault.

I would like to build the source with globals left in and run it under a code analyzer to see if there is a consistant point of failure, but I need to do some kernel testing (issues with multicasts over wifi) and so I cannot downgrade enough stuff to get planeshift to build.
I did run some straces against it, but the results are inconclusive:
Everything looks normal and then:
[pid 2730] gettimeofday({1146186829, 581948}, NULL) = 0
[pid 2730] gettimeofday({1146186829, 581984}, NULL) = 0
[pid 2730] gettimeofday({1146186829, 582024}, NULL) = 0
[pid 2730] --- SIGSEGV (Segmentation fault) @ 0 (0) ---
[pid 2732] <... futex resumed> ) = -1 EINTR (Interrupted system call)
[pid 2738] <... select resumed> ) = ? ERESTARTNOHAND (To be restarted)
[pid 2732] +++ killed by SIGSEGV +++
Process 2732 detached
[pid 2738] +++ killed by SIGSEGV +++
Process 2738 detached
Process 2730 detached
Not a clue as to where it failed.
