A couple of the Vic MR2 Club members run 225/50R15 Falken ZE912 on the rear of their sdubs, and they say they are not too bad.
As for the Hankook 457's, I just checked out reviews of them on several sites (in the US and locally) but could not find the critical 225/50R15 size listed.
I also note that the Jax website has Nexen 225/50R15's for $135 ea, but I don't know if they are any good
They also list 225/50R15 Pirrelli's for $339 ea (gasp).
Somebody told me that they sell those to owners of early model Lambo's and Ferrari's.