I've never driven them, but Evomrguy drives a set of RT-615's and he says they do get squirrly in the rain.
Right now I drive a set of Kumho MX's and never had a problem in the rain, however I'm not getting another set due to its softer sidewall.
I am looking into getting Dunlop's Direzza Z1 for my next tires.
Dunlop Direzza Sport Z1
I haven't seen any negatives about this tire yet (online reveiws/other foums).
