Dan, There is nothing wrong with trying new ideas even after finding something that works. You may find something that works better for you or gives better results than a previous good method. I have seen many of Eric's videos, but have not seen his mountain building ones. I modeled in N scale and HO scale over the years. In fact my last N scale layout was the one I got the farthest along on scenery, and used foam and hardshell both on that layout. I'm looking forward to seeing your progress, as you know I'll be ready to start scenicing my layout as well.
How can you go wrong if the grandkids love it?? 
