Playing fast doesn't always mean playing well.

You're right. It's better to think it through, but some people can spend an hour thinking.
As for the pros—simply put, when you encounter Pros in Heroes, it just comes down to luck and who bought more troops and found more artifacts, including magic. And I think it will be the same at the tournament. You won't beat me like some noob who didn't know who is stronger, an Archangel or a Devil, or which artifact is better to equip, the Centaur's Axe or the Sword of Justice, or what a certain spell means or what a specific combined artifact consists of. That won't work with me; I know everything in Heroes, I think it's the absolute limit. I've been playing them periodically for 6 years now. It all comes down to who gets lucky, who calculated correctly, and who miscalculated. That's all. But I have no experience playing Heroes online, so it'll be a bit nerve-wracking; because of this, my chances of losing increase beyond the standard chance. I only had experience in Generals. But as they say, you can't drink away your experience :)