Mercurial has the LargeFiles extension[0]. This ships with Mercurial by default, just disabled. This does help some.
It's really disappointing to see 3.0 announced with no solution to this.
And what kind of data corruption do you see? It tracks files by their SHA1 value and downloads them as needed. Did you report any corruption issues you hit? Or have links to anything specific?
what client do you use?