Couldn't you simply link dynamically to PhysFS?PhysFS would then be statically linked to 7zip, which would be allowed, but your app would not be statically linked to 7zip.

Yeah I thought about that. This would technically make it physfs's problem :)

I guess I should have researched this first, but lzma is dog slow anyway so it's better to stick with zip for asset storage in physicsfs:

http://bashitout.com/2009/08/30/Linux-Compression-Comparison-GZIP-vs-BZIP2-vs-LZMA-vs-ZIP-vs-Compress.html

The massively longer decompression times for lzma would make the loading of assets a ton slower for marginal space gain. Speed is more important than size with asset loading in my opinion.