What do we think of Rustoleum Rust Reformer?

I've found a few little underbody spots with scale corrosion (a few points along the pinch welds) that I should really hop on soon. I've heard mostly good things about Rust Reformer, although not much in the way of long-term accounts. It will be topcoated with gloss black, then Fluid Filmed every year and run through an underbody wash in the winter every 10 days or so as per usual if that makes a huge difference. Anyone have experience with this stuff?

It works OK to get a paintable surface as long as the rust hasn't progressed super far- make sure you wire brush off any really scaly stuff first and put several layers of (also Rustoleum, for compatibility) paint over it afterwards.