I was just looking at this weekend's Thorndon mile, run under set weights and penalties conditions, which the WRC seem to love.
Clear top weight Mali Ston, the winner of five races and $148,000, rated 90, has to give weight to The Chosen One, rated 107, the winner of 6 races and $2,219,000. Interestingly, the bottom weight in the race, Mai Tai is rated 92 and has won six races and $162,000: and was beaten a nose by the top weight last time, meets him 3kgs better off this time.
Under normal handicap conditions the weights would be totally different and under WFA conditions they would also be different. I struggle to see the merit in this SW+P idea; it certainly doesn't lead to bigger fields. Logically, the top weight should have no chance in this race. This is NZ racing though, so who knows what might happen. If it did happen to win it would be weighted out of NZ racing after having had just 8 starts in its life. I don't know if there is some special way to work out rehandicaps in a SW+P race.