Bruce,
Does your
motor have a port (instead of the "ears") to conveniently do a fresh water flush? This will make it much easier to flush.
Suspect most do not flush their motor because they need the ears to do it or they just didn't think about it.
Wouldn't be a bad idea to flush an
aluminum block OB w/fresh water to increase it's life.
Depending how much you are using the OB (not everyday) and if you have extra fresh water/the time, why not.