thanks for the thread, very interesting. I suffered a drawdown of 40% earlier in the year (and recovered) (This is for an extremely aggressive system). One thing that might be of note is the method of drawdown, ie when I looked at the top 10 drawdowns in backtesting, the rate of descent, the overall failure of the system was consistent. It helped me get through it. If it had veered way off, or the system started failing new REASONs would be cause for concern.
I hate resizing because often the best recovery from a DD is right after it (ie your system goes back in sync with the market).
of course, it could never go into sync. My personal rule of thumb for trading aggressive systems would be to stop after a loss of 150% of max DD.
so if your max dd is 40%, than you would lose up to 60%.