Wick, I've played with many StarCraft I players in Warcraft III, and I think they all showed decent results (Strelok, te4ka, etc.). It's not that difficult; it's just that in StarCraft, macro is key, and it's easier to play because there are no heroes, and you don't have to use such combo abilities as in Warcraft III. And there are no items there either.
Who knows, opinions probably differ here. Personally, I tried StarCraft I, and I had enough skill for control, but I didn't know the builds and strategies, but that's easy to learn :D
By the way, we've strayed too far from the topic... what do Warcraft and StarCraft have to do with it? We were talking about Heroes!)))
Imagine if Ubisoft comes up with something and tries to promote Heroes 5 or 6 as an esport. That would be hilarious! But it's possible; they're currently making an MMORPG based on Heroes and a famous browser game. They have the money; they can... the question is whether Heroes 5-6 will be accepted as an esport. After reading reports from top players of the 5th installment, I was laughing. Our reports are written by noobs who have only played 10 online matches.))))