I stewarded a Bath Rugby game while at uni.
Apart from somebody in the crowd getting hit on the back of the head with a ball that the players were kicking about before the game, I have nothing whatsoever to report.
I've been to a few [3?] rugby league internationals. The crowd at those didn't...
Without particularly disagreeing, I don't find there's a great deal of difference between the atmosphere at an ODI or Test Match compared to most home stands. Albeit I tend to go to the louder (and cheaper) stands like the Hollies or the Western Terrace when I go to the cricket.
Having said...
At the Middlesbrough FA Cup game last year, I was struck by the presence of numerous small children running around the concourse at half time in Brighton shirts, with quite strong Leeds accents.
We come from everywhere nowadays.