I don't believe anybody in THIS thread has advised using an asymm in 25 kts of wind, nor claimed that its easy to do that. Including me or Mariachee.
In 25 kt TWS, most semi- and full-displacment hull sailboats have more than enough power to sail at max hull speed without a spinnaker (displacement or semi-displacement hull speed).
A spinnaker comes into its glory for cruising in between 4-15 kts, when the boat is sailing at deep angles. At these wind speeds and these deep angles, the apparent wind speed is under 10 knots apparent, and the boat can benefit from the additional power afforded by an asymmetric. On many boats, the asymm provides enough power to increase downwind VMG by 25-50% at deep angles, in less than 15 kts TWS.
For example, on one of my previous boats, using the asymm in about 8 kts of wind increased my downwind speed to 6 kts, vs with main and genoa 4.3 wing and wing. That makes a significant difference in the distance I can travel in an hour!
Judy B
Retired sail loft owner.