I am not changing my stance on that.
His contradictions come between what is on the tape of the call to the dispatcher and his testimony at his bail hering. To the dispatcher, he strongly implies that the thinks Martin is armed ("He's got his hand in his wasteband") which would bolster a claim for self defense. And his bail hearing, he claims he didn't know if Martin was armed or not which dilutes his initial implications.
During the call, he claimed that Martin looked to be in his late teens. At the bail hearing, he claimed he thought Martin was a little bit younger than 28.
Given two slip ups in a few minutes of testimony, I would be surpised if they risk putting him on the stand again. This presents a problem for the defense as a self defense claim will be more challenging if the defendant does not testify.