Anyone used underlay under a rug?

[Discontentedpony]

To reduce impact noise to neighbours below?

Don't want to have to carpet so thinking a shaggy rug with underlay, something like cloud 9, might reduce footfall noise.

Would underlay work under a rug or just be a massive trip hazard? There are only certain high trafficked areas that are a problem so carpeting seems unnecessarily inconvenient and a massive job.