yes gaara would crush haku as a bug, that I agree to but I think that Haku would be able to beat him if as stated before survived the battle against Kakashi and his team.

Haku in that fight was superior to sasuke, which is Konohas strongest genin and the "last" survivor of the Uchiha Clan. Sure Sasuke was able to predict the movements but he would have lost the fight anyway even if Naruto wasn't there. I think Haku would be the greatest genin ever and would bypass Kakashi and other Jounins level if he would have a couple of years training. To bad he died so early, otherwise he could as well be a Jounin himself.