Vincible: I was responding to KaC comment - t2s4s2r3r1t3s1 is a KO, not alive unconditionally. But I agree, this is better defence than provided at the moment.
caranthir: The currect defense is gote seki for the defender. Not possible to compare in exact terms to the ko variation - would depend on ko threats in a real game. But living with points is very small extra, so the seki variation would be almost always better.
I was responding to KaC comment - t2 s4 s2 r3 r1 t3 s1 is a KO, not alive unconditionally. But I agree, this is better defence than provided at the moment.