They talk about changing the front forestay adjuster to adjust rake...
Don't think it's wrong advice, just communicated not so well at times.
I've raked back in moderate winds and the Wave's butt sits down in the water and won't move. Really was kinda funny.
With mast raked back in moderate to low winds, I may use the rudders more as daggerboards but the trade-off is that I can't tack fast because it gets butt heavy, even when trying to keep my weight balanced on the boat.
This is just my opinion.
IMO, just as important as raking in high winds is making sure the sail is as well shaped and as flat as possible by downhauling and making sure your battens are doing what they are supposed to do.