We fly our 1000-1200 ft. sq. (I forget exactly) tru-radial asymetrical (yes tri...) from an ATM bag in anywhere from 5-15 knots apparent. At the low end of the range it is skill, at the upper range it is nerve.
We get about 1/2 the apparent wind speed in boat speed, sometimes better, depending on whether the main can really be effective w/o blanketing the chute.
The problem with the high end of the wind is that the bag becomes difficult to use to collapse the chute and you are faced with the old methods, which are difficult if you are short handed...