Frankly, a round wheel is the easiest of all. And don't think 55lbs is not enough. It'll take care of almost anything on North America if you can hit the lung area--including elk and moose.

Now you want to shoot something that draws easy and produces a lot of speed (which helps with the penetration anxieties) try shooting a Martin bow with the Nitrous cams. Mine is generating 280fps with a hunting setup----27.5" draw and 55lbs.
Preferably look at the Cougar III or Shadowcat. I have the SlayR. A bit heavy but I like em that way.