At heart, when it comes to adaptations, I'm a purist. Movies of 3 + hours have been successful, as long as they're done well. Or, release a trimmed down version of ~3 (several action movies are coming in at 2.5 hours or a little more) to theaters and have the Bluray/DVD have the complete musical. All though I'm a purist, I will say I can do without Gavroche.
BTW, anyone seen the new traveling version, I've heard that it is a bit different from the original (different staging). I don't know if it's shorter, but I'll be seeing it in January.