Stronger compression algorithms for faster transfer on slower networks

[M-Gonzalo]

I'm currently working with a setup that has a slower internet connection than your typical lzma throughput, which is sadly still pretty common on huge parts of the world.
On cases like this, using something slower like --zc=lzma or similar would counterintuitively mean finishing earlier.
Of course we wouldn't want to include some esoteric formats that might give better compression at the cost of nobody actually having them installed. 7z's algorithms like lzma2 or even ppmd if it's just text files seem like a safe bet though.