Optimal would be the answer. Level at Brittania Peaked at 4.5 last year(same then level 6 competition held early may) it’s almost there right now.
Full eddy service, 1st wave too fast (may be for your fast dragorossi boats), 2nd wave has a nice green shoulder for vertical moves and is very sticky throughout)
3rd wave is also nice but a bit shallow.
Crowding is a problem, I recommend you avoid peak hours ie late afternoon if you want lots of time on that great feature.