We have had some severe knockdown over the years, we sailed for over 20 years in a very windy area. With white sails we've never had an issue with righting the boat once the gust passed or we'd rounded up again.
Once, we were 'pinned' with 4-5 feet of the mast in the water and the boat floating keel past horizontal (luckily flat water and nothing went down the companionway) In this case the partially raised spinnaker 'filled' underwater and, as it turned out, did this when wrapped around a shroud. Once we figured out why the boat wasn't coming up on its own (and retrieving our two wives who'd fallen out of the boat) we blew the spinn halyard. The boat instantly righted itself, but the several hundreds of pounds of water in the spinn in the rig ripped a spreader off. We got the main down smartly and motored home, saving the rest of the rig upright.
But with white sails we've had plenty of 'wipeouts' with no worries other than a lot of water in the cockpit. (btw 2 panicky people with buckets are very efficient bailers!