[FitGirl]

Thanks for returning to the project, deduplication is a very useful feature.
I have an idea which will reduce the required RAM for dedup. You may store some rare/large duplicated streams in a temp file, while storing small/frequent dupes in RAM - this way the excessive HDD load won't happen, cause reads will be rare and the RAM won't be used that much. 1-2 GB is a pretty big amount even for machines with 8 GB. And for users with 4 GB installation will be almost impossible, considering srep and lolz/lzma. Even with page file. So reduction/control over used RAM is a must, I think.

I'd recommend you Halo Reach for testing dedup, it has tons of duplicate streams of a different size.