I tired some trials with steam a few months ago and was not really happy with the results. I really liked the idea of steaming as to avoid issues with water maybe getting in where I did not want it on double barrel sets. But when I tried steaming, I just had way too many issues with condensation building up and creating spotting in the finish.
I was able to play with things enough to kind of get decent results (i.e.: when to put the part in the steam, and whether to pre-heat or not) but I was not comfortable with it and just scrapped it. Boiling is way more predictable and reliable.