Don't quote me on this, but I seem to recall that going from V5R4M0 to
V5R4M5 wasn't much of a leap. I think you get virtual IOP out it and
not much more (someone please correct me if I'm wrong). When we moved
from an 810 to a 525 we were told to upgrade to V5R4M5. I wouldn't
waste any resource upgrading to V5R4M5 unless it was necessary.
Again as I know nothing about your iSeries other than you are at
V5R4M0, that is only an opinion.
Hopefully my answer was as vague as your question. ;-)
Thad Rizzi
v5r4m5 just adds support for a new piece of hardware, whose details
escape me at the moment...but if you aren't changing any hardware at the
moment, you wouldn't gain anything by doing it.