As far as spring goes, the Flint honestly wins. By at least a mile. Now, I'm not a big 'spring' guy anyway... but the BSR's offering is almost completely unimpressive IMO. Not a fan of that at all. Conversely, I think that the Flint's spring algo is at least as good as the Eventide Space (though, obviously not as flexible) and considerably more realistic than the BSR.
I briefly compare the two a little bit toward the beginning of this video: