[tptacek]

I wouldn't actively recommend it. I would worry if someone was using Rijndael-128/256 to make a hash function. But apart from that: the gain in reduced malleability probably offsets any reduced security margin; in other words, using a larger block makes the realistic attacks somewhat harder.

There are probably zero crypto implementations that that contain the string "AES" that use Rijndael-X/256 that aren't broken in some other comical way.