When you say "works really well" does this mean that there are no little rust bumps showing in areas that were pitted a year or more after final paint??
The local autobody shops in my area using rust converter have trouble with the rust coming back after less than 1 year --starting with little bumps in the final paint, and big chunks of paint falling off in 3 years ---I have seen this happen with the cheap and $$$ paint jobs.
So far the only method that has worked for me in the long term (more than 5 years of normal outside parked driving)) with no reoccuring signs of rust or paint failure has been sandblasting,picklex 20, epoxy primer, surfacing primer---etc under the final paint,I would like an easy miracle method other than sandblasting that works in the long term.