False !! I'm an almost exclusive phantom player and i have some top 10 on all classes. I didn't spent 1% of the time i spent on phantom TT/SL on the lower speed classes. Obviously doing all those nose down/up/sideshift BRs on slow classes is something which requires skills, but IMO any top 10 phantom pilot can reach a top ten in slower classes IF HE TAKES TIME FOR THAT GOAL ! Some already did (Yeldar as a known example). Items pick up is a major part on winning at phantom speed. It's multiplied on slower speed classes. The weapon hit's slowdown below phantom is huge and you lose easily several seconds and it's far more difficult to catch the first pilots than in phantom, because everyone can avoid walls, have decent lines and hit all the speedpads on slow classes. I was recently invited on rapier races by a french mate, we did some single races and 2 tournaments. On the first tournament i was hit by rockets/missiles or mines/bombs at almost each races and i lose with easily 3/4 seconds left. On the second tourny i was lucky with weapons and won all races with 5/6 seconds = 100% luck !! If rapier/flash/venom races require as much skills as phantom, why didn't any of the WIPEOUT HD CUP slow classes pilots CHOSEN NO WEAPON RACES ?
That said The cup's rules allow slower classes and it's a good thing because it attracted more people on the event ! Will the winner of the cup be the best wipeout HD online pilot ? Probably because when you look at online races phantom are the lesser ones! Will he be the most skilled ? It's another story !