Roughly the upside is that (in theory) the attacker needs to defeat each cipher separately (barring that the combination offers some shortcuts where one cipher

Roughly the upside is that (in theory) the attacker needs to defeat each cipher separately (barring that the combination offers some shortcuts where one cipher interacts with another so that some computational complexity can be eliminated). Downside is that the performance takes a hit (processor/bandwidth [if blocksizes don't match, dunno if this is an existing risk]), which might not be trivial. Disclaimer: I assume that existing, proven implementations are used and out from one cipher is handed over to another as input, keys and IVs and other crypto mumbo jumbo are not recycled and that the implementation does not offer new side-channel attacks somehow etc etc. Personally I'd wait for a while to allow more competent people to analyze the library. In the meanwhile one can do performance profiling to roughly calculate how much beefier servers are needed in a real-world scenario due to extra crypting and decrypting :-)