FYI Mercurial has time-based releases. So 3.0 doesn't mean anything special (it's just the next feature release after 2.9).
Why intranet only? The data still comes from the HG server through standard means.
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?
Largefiles are being used for production in game companies and we have not gotten reports about corruption.
It's really disappointing to see 3.0 announced with no solution to this.