A big Alaska moose weighs as much or more than a Cape buffalo bull and nobody uses solids for moose.
The PHs I have discussed this with recommend a soft point for the first shot and solids for the follow ons. The theory is that you don't want the first shot to pass through the animal on possibly a broadside shot but the second shot will likely be as the buff is running away (almost never directly toward you, BTW). A solid penetrates further through the large amount of undigested grass in the buff to hit the vitals, or so they say.
My last PH recommended softs for the first two shots. Some recommend against using solids even for follow on shots.
