I disagree with the "go with metal" response unless you don't care about how it looks. Metal doors are cheaper but don't look that great. The look of a door like ThermaTru is very attractive. Even with close inspection it's hard to tell that it's fiberglass. Drillng is a little more difficult because it's simply a tougher more resilient product. A solid oak door is more difficult to drill that metal also, but look what you get. How many times will you be drilling your door? ONCE! I have a fiberglass door and I love it. I can't even recall the drilling process, but I now have a beautiful door with a lifetime warranty.