Again, knowing nothing about Steelflex I could not say. According to the adds it's a durable Paint. Don't think it's in the same classification as Steelflex, unless Steelflex is classified as a paint; But as a paint, I guess it all depends on your prep and primer. I have read were it has lasted for years and retained it'd gloss; However, I guess that would depend on use and care. I think your question may better be answered by someone else as a New Topic.
If I remember right I did hear about Steelflex being used the same way Glovit is used, I could be totally wrong though. I used Glovit as my base inside and out prior to any paint or primer.