Is multibos really needed on each sp update on a hacmp config?
Is someone using it?
I have an up coming update and I don't have time to understand this technology. Does SP update might screw you up and you can't restore properly from it?
HACMP 4.5 is not supported with AIX 5.3. So I believe you mean HACMP 5.4.
You don't need to use multibos. However it is a good idea to have some means to return to the former software levels in case you end up with some AIX-RSCT-HACMP combination that does not work as expected. Using multibos or alt_disk_install makes your life much easier if you don't have a testserver.
Remember that you will have to do a full clustertest after the upgrade.