10G/11G RAC on AIX P570

Im looking for user experiences from anyone running 10g or 11g RAC using Oracle clusterware on AIX. I read different articles, an AIX RAC cookbook redbook (which BTW is excellent) and Oracle manuals but getting different  best practice advice from each. One document says to use GPFS for the RAC shared filesystem and the other said to use RAW shared physical partitions with ASM.  Anyone have either of these configurations ? Any issues ?. We are thinking of having two shared partitions(cloned) with 32 virtual CPU's and 32G memory to match on each LPAR node contained in a pSeries P570 running AIX 5.3.  I understand ASM became