I have been told by the distributor here in Holland that the 18S20 either is obselete or will become obsolete in the near future and only the 18B20 will be supported. I don't know if that is only a European or even Dutch thing, but we have chosen to use the B20 for that reason. As far as I can recall, the hi-res data is retrieved in a slightly different manner than for the S20 so this may be something to consider for you as well.
We have a number of sensor-rungs installed on a couple of chemical tankers for cargotank temperature measurement as a field-test and so far it all seems to work as one would like to expect.