SS2 Vegeto

Well, judging by Byakuya's attitude towards him, even though he's quite arrogant, he probably had the edge using his shikai to attack - then again, Ichigo wasn't really straining himself or having a hard time before that point either, since he was fighting an unreleased Byakuya, so he may not have had that much to go by..and although he would have realized the opponent didn't seem to be fully exerting himself, not only because it should have been fairly clear after a while of fighting him, but..because Ichigo said it himself before he released, I doubt he would have fully grasped exactly where in was, as compared to him, but the fact remains, he appeared rather certain that he could handle the situation at shikai. After Ichigo used getsuga tenshou, however..he was able to blow away the thousand blades set to attack him, and Byakuya was narrowly able to dodge. Ichigo then insisted that Byakuya use his bankai, and attempted to challenge it at shikai, and although Ichigo gave himself a slap on the hand afterwards for even..considering that he might be able to do anything against bankai with shikai, it shows that he was very confident in his ability. So, I believe that should answer the question.

__________________