I reckon they'll water any firm ground out of the course, at least ahead of today, plus the first 5f of the SJP course is on the round track which wouldn't be as fast anyway as the rest of the course, plus it's uphill so I can't see it being too much of an issue, at least today, and it did beat standard time at the Curragh so the ground must have been on the fast side that day.
For me it's definitely the percentage call but whether it is betting material might be another matter.
There isn't enough water in the taps to stop it being rattling ground today.