I've used both cheap steel pans and cast iron, and while the effect is less it still turns my sweated onions into sauteed onions intermittently. I'm glad to hear that mine is just built cheaply and that proper induction tops can handle consistent low temperature better. Still not buying one without trying it, though
Honestly, I would love a stove that's just a 3" thick steel top with induction burners on one side. There would be a steady temperature gradient the whole way across, and pans of any size, shape, or material could be put anywhere on the surface for just the right amount of heat.