This is the line of play suggested by nomad, 4d* IGS.
White 1 looks promising. It leads to ko, but one that favours White.
Playing 2 here is a good response and will lead to ko. The ko favours White.
DaveSigaty: I think this ko doesn't just favor White, but actually is hopeless for Black.
Black is in atari and there are no internal threats.
This 2 also seems to go nowhere. If 6 at 7, White plays 6 and clearly leads in any capturing race.