I agreed. After all the screaming and singalong at least you can get some water handed out, if you are close enough to the stage. I think 12pm would get you that close so dont worry.
Anw this is my first time getting seated ticket so idk what the queue for that would be like. I hope that it wont be as long as the standing queue.
I'm currently looking at CAT1 or 2 seated tix. I would have opted for the standing one too. But since my experience with mosh pit at Muse concert last year, unless you start queuing at 7am, your view will probably not that worth it. Besides, from the look of the stage set-up, I would really love to look at the entire stage!!!