You keep saying that ext3 is superior to HFS+ but you still have not said why. On what grounds are you basing this? Also without knowing the the environment and switches used for the bonnie++ benchmark, those results have to be taken with a grain of salt. We do not know for example on those results:
Was the partitions on the same area of the area of the drive? Location of the partition can greatly vary results.
What block sizes were used on the partition?
If it was a raid, what type of raid? Chunk size? What stripe size was used? If raid 5 what parity algorithm was used?
Is barriers being used?
All these items can cause a system's I/O results to vary greatly.