[danallison]

You should use whichever tool you prefer, of course. But it sounds like you're asking about how Calculist is different than Org-mode. The two have a lot of overlapping functionality, but Calculist is a little more friendly and approachable for non-techy people, and it has a cloud-based web version for collaboration (in addition to the local desktop version). There are other differences, but those are the main ones that come to mind.

[akho]

The “more friendly” claim needs to be backed up with experience. I don’t think any of the similar products (numi, Calca, …) have reached a wider audience than Org. Excel, of course, continues to dominate the space, despite being much more complicated than all these tools combined.

The web version is not for collaboration, it’s for subscription income.