I will preface this by saying I have no vested interest in this company and I have not used their products. My interest is simply in their claims of superiority.

I noticed on the restoration site of AT&SF 2926 a thank you to "Rust Bullet", so I had to know what it was. Anyhow after navigating through the site, several thoughts stayed in my head...
1. Virtually no prep work required other than to remove loose scale
(i.e. no sandblasting or grinding required)
2. because the product is self levelling, minor pitting would be covered
3.After it is cured it is nearly impervious, and is UV stable
4. can be applied by brush, roller or airless gun.
5. it actually forms a bond wih the underlying metal, so it won't flake off

Sounds perfect for restorations of coaches, tenders, diesels, freight cars etc. Imagine trying to sandblast the inside of a rusty tender, vs vacuuming up the loose rust and spraying this stuff on.

The only drawback is that it will not resist high heat applications, so boilers are out.
Other than the cost, its hard to see a downside to this
http://www.rustbullet.com/Products/Automotive/train.htm