It sounds from interviews (Todd Marchant, Sam Dickinson, Grier) that Haltts really needs to work on his conditioning. Dicky said Haltt's pregame meal is pancakes with syrup, and Marchant talked extensively about Haltt's work trying to get his weight under control / nutrition. He has the opposite problem of some of SJS's stick figure prospects. With that in mind + his dev path (great shot, could round out his game) I'd be slightly in favor of him heading to the AHL this year to step up the "pro hockey" lifestyle and work on ES play and translating his shot to a higher league.
Of course, if the decision is for him to go back to Juniors and play a bigger role in London, I'm sure that's fine too.