Ask HN: Do you recomment mercurial hg with subrepos, what's best practice?

I have a project with many sub tasks, each has large size test data, so cloning or branching entire repo is a big waste of disk space, so I decided to convert hg repo into smaller repos for each task (using hg convert extension), so I can branch it, experiment with code, then merge back without affecting the entire repo

so, I could either manage those sub-repos manually, or use use subrepo extension.

anyone with good or bad experience using subrepo extension, does it save time over doing the managing myself of subrepos