The thing about a 5v5 is that allowing arty makes a huge impact. You can't bring more than 1, or the enemy attacks. Yet arty can make too much of an impact by getting the first kill. Once you are up 1 kill it's a huge advantage. In a 15v15 if you lose a tank that's 7% of your forces. In 5v5 it's 20%...
I would love to see a tourney with 6-8 players each side and a limit of 1 artillery. This way you can either defend or attack. There's more tactics. The maps won't feel so big. And getting the first kill doesn't determine the outcome of the battle so quickly.
That said - tourneys > CWs and I absolutely love 'em!