[capableweb]

One set work with maintaining old software for a national bank and the other set work with software for a huge international company that are not IT focused but ended up with software and firmware that just been ticking along since forever.

I'm not jealous and don't think I would bear working like that every day for months. Take a hard look and try to build software with Forth before you try to use it professionally.

[exikyut]

There's a reasonable number of people out there who would be very interested in a disambiguation of scale, architecture, implementational wins/shortcomings, etc, about these two cases.

Codebase size? Entropic/organizational complexity? Word style? Environment (custom/standard)? Standard(s) used? Ease of debugging? Testing methodology used?

I most definitely am not literally asking for answers to this set of questions (considering the cases of a bank and an industry that presumably doesn't want to be known for its software) - I guess I'm just being exact in the gist of my curiosity :)

The only interesting illustrative example I can provide is that Mattel once used Forth for its toys (quoting previous times I mentioned this: https://news.ycombinator.com/item?id=21823216, https://news.ycombinator.com/item?id=17755287)

I don't know of any recent case studies.