buddhata: @Farkas, is it not about challenging but about the best move possible? B1 and X lives but in gote, D2 and X lives in seki but in sente. However, if there is a move that is worth more then 9 points on the board it makes sense for the opponent to play like this and keep sente, if not, better to make seki in gote... But why would the opponent sacrifice 2 extra stones just to keep the sente? Only as Ko threats... In this case, at least both options should be included I'd say...
d4rkm4tter: Best move possible is often tenuki, so it is most of the time about the challenging plays.
@Farkas, is it not about challenging but about the best move possible? B1 and X lives but in gote, D2 and X lives in seki but in sente. However, if there is a move that is worth more then 9 points on the board it makes sense for the opponent to play like this and keep sente, if not, better to make seki in gote... But why would the opponent sacrifice 2 extra stones just to keep the sente? Only as Ko threats... In this case, at least both options should be included I'd say...