The current Blade internal downhaul will provide right at 10" of travel. According to Charlie at Ullman, the sails only alow for about 8". Beyond that you are doing some strange things to the mast. I usually put just a little pre load on it so would theoretically have more room, but anywhere after about that 8" the mast top is screwy and it does not like to tack over.

I checked mine this weekend. What seemed to be a good up wind setting all the way till we were double trapped was right around 5" down from the fully relaxed position. Later in the day as the wind picked up we went up to about 7". There was probably about another inch to go before we would start adjusting other things to continue depowering if the wind continued to build.

Matt