> Domain expertise + tight feedback loop

This is the answer to a happy B2B SaaS implementation. It doesn't matter what tools you use as long as this can be achieved.

In the domain of banking front/back office LOB apps, if you aren't iterating with your customer at least once per business day, you are definitely falling behind your competition. I've got semi-retired bankers insisting that live edits in production need to be a fundamental product feature. They used to be terrified of this. Once they get a taste of proper speed it's like blood in the water. I'm getting pushback on live reloads taking more than a few seconds now.

Achieving this kind of outcome is usually more of a meat space problem than it is a technology problem. Most customers can't go as fast as you. But the customer should always be the bottleneck. We've done things like install our people as temporary employees to get jobs done faster.