Unfortunately, geting bit-wise floating point exactness is incompatible with using primitives (or even, to a certain extent, subfiles). Much of the time, curved primitives meet other curved primitives, but sometimes they have to meet part-level geometry, and when they do, the floating point values won't match. (Note: parts aren't allowed to use a bunch of floating point digits when specifying geometry). Also, even when primitives meet up with each other, they're only likely to have the same bit-wise floating point value if both primitives have the same transformation matrix. Otherwise, it's quite likely that round-off will result in slightly different values.