[simonmic]

At a certain point darcs was fixed to make the exponential merge case much more rare, though it has never been entirely removed. At least from that point on, it has always been possible to use darcs productively just by avoiding or working around those very conflict-heavy merge scenarios. Regular darcs users internalise those working habits and so rarely encounter the problem in practice.

If you do encounter a slow merge with darcs, the normal practice is to treat that as a mistake, step back and re-do your commits to be less conflicting - not to waste time waiting, ending up with a very slow merge in your history.

The original exponential merge corner case, and subsequent lack of a clear prevention mechanism or even clear description of the issue, has had a big anti-marketing impact, and has probably kept darcs out of the limelight ever since the departure of the original lead developer, despite a small heroic band of maintainers working on it to this day.