Yeah, the difference in representations could be a problem. I think a lot of it could be dealt with (with much difficulty) by the compiler -- for instance, you

Yeah, the difference in representations could be a problem. I think a lot of it could be dealt with (with much difficulty) by the compiler -- for instance, you might be able to use the mantissa bits as a two's-complement int and synthesize proper arithmetic and comparison behavior out of unholy combinations of floating-point operations -- but in general, if someone depends on the bit pattern explicitly (as in compressed data, bloom filter, bit flags, ...), you're going to have a hell of a time getting correctness, much less performance.