I have not cut any sheet stock such as this, the only titanium I was involved in cutting was plate arount 1" thick. With that we determined that the sames specs as for cutting steel worked best, with slightly faster speeds.
What was the problem with piercing? I would expect it to actually pierce daster than steel, which would mean a shorter pierce delay time. Also, on 20 ga I would set the pierce height the same as the cut height.