I like a bigger Henderson in this fight. His wrestling and striking is better, but Hughes would have a submission advantage.
On a semi-related note, I was watching a replay of Franklin VS. Tanner for the UFC Middleweight title. The stipulation was if Franklin won (which he did), he would get to coach the ultimate fighter. Hughes and Franklin didn't fight at the finale because they were friends. If Tanner won, however, he would have coached that season of TUF and fought Matt Hughes at 185 at the finale.