@crashino, will it be a continuous competition? Will it be up for October too? I would recommend you to have a customized competition for bitcointalk only too. That would benefit you more.
Comparing the result of the onsite crash challenge to the one namely btcgosu x crashino in this forum, it is clear that the interest and number of participant is bigger in the btcgosu x crashino.
With that fact, I think it would be more competitive if the crash challenge is run in this forum.
Crashino won't receive the same attention from the Bitcointalk community if they want to run a crash challenge alone. There were some participants in that contest who follow btcgosu posts always. 'efialtis' had also tried to attract many users in that contest. You wouldn't have seen same interest from the forum members if it was maintained by the crashino representative alone. I think that the crash challenge will be more competitive if the leaderboard gets updated after every few minutes.