Well, then, do your own penetration tests shooting both round balls and the Lee Precision, R.E.A.L. bullet.
Get some one inch lumber, and make a box that spaces the panels one inch apart. You will need at least 12 boards. Shoot your best load at 50 and 100 yds. See how much penetration you get. Try this with both pure lead and Wheelweight balls.
Then do the same test with the Lee slug. Make your choice on what you learn, not what you hear, or " think ".
I did the penetration tests years ago with my .50, and I know what my .50 will do. It will kill Elk inside 100 yards, and probably Moose, too. I would prefer to use a .54, or larger caliber RB than my .50, because I know that the weight of the ball is going to determine the depth of penetration, much more so than velocity. Once you get over 1/2 ounce in weight, you get incredible penetration on any living flesh with a round ball. And, the added benefit is that the ball expands in tissue, causing internal shock to the vital organs to put the animal down quickly. A slug will penetrate further, but is much less likely to expand.
The decision you make is based on competing concerns. Are you likely to be shooting through massive bones, or Gristle that required deeper penetration, or are you shooting into softer tissue that requires expansion? A moose is huge, but its a relatively easy animal to kill. Its no bear, for sure. If you were talking about hunting bear, I would not hesitate to recommend that you consider only the Lee Slug. You are handicapped enough by using a single shot firearm when hunting bear. You need all the whomp and stomp you can get when hunting a animal that might just fight back!