The starting heroes have a significant impact. Especially when, as Rampart, you get Vokial as your second hero, while your opponent gets Galtran (a real example).

Galtran won't appear.

We can also discuss Luna and Solmyr. And, by the way, about Bron and Illor, I think that's what you mean. Let's also remember Tanta. In general, it feels a bit weak to exclude such iconic heroes, who essentially define the gameplay for a faction, from the tournament – Dungeon without Shakti, Stronghold without Tiras, Inferno without Kal'hak (all about HotA, of course). Thor keeps all of this and maintains some balance.

But this is still just a suggestion.

P.S. @Toga: I didn't quite understand the point about balancing the odds. Are you willing to give up all 10,000 starting gold for a particular starter hero? If not, then everything else is the player's choice, and the consequences will directly depend on how well they assess the hero.