Weight limits are set at very reasonable expectations for the hardware to handle. Not really related to the righting moment or how much power you can put on the rig.
For maximum wind... We rely on your local coast guard recommendations. Maximum wind is the small craft advisories limit. It varies by region due to differences in wind and water conditions. http://coastguard.dodlive.mil/2009/10/small-craft-advisories-and-boating-safety/
The small craft advisory is a range of wind speed and wave height. We would not advise sailing in anything entering the small craft advisory range.
Most small craft advisories go into effect at the low to mid 20 knot range. In California that is at 21 knots, so 20 knots would be the max we would suggest there.
Warranty does not cover sailing in small craft advisory conditions.