The Mahogany they use is typically "Eastern Mahogany" or Nato. It is not technically related to the African or Honduran species Mahogany, but is very similar in grain. I don't subscribe to the idea that certain wood species are inferior or superior based on what continent they happen to grow on. The density of any wood species can vary significantly between any given cut. You'll find very light cuts of Honduran Mahogany used on Gibsons as well as more dense cuts. As you say, the poly finishes Epiphone uses are very strong, so I'm surprised that you found any of their guitars easy to dent regardless of the wood density.