RE: Caliber and bullet choice for Deer. Why so heavy?
I use the lighter bullets per caliber as well. Everything you say in your post is pretty much true. However when you use the lighter bullets, shot placement becomes more important. Poor shot placement will result in excess meat damage and or poor killing power. Heavier bullets get the job done but the lighter bullets give a quicker and more dramtic kill.
That said, I don't go to light. I stay away from bullets lighter than 150 in the 30 caliber because they are intended for Varmits. I wany the SD of my deer bullets to be 200-225. A bit higher yet for elk and moose. If high velocity will be used, then I will up the SD a bit more. The Ballistic tip is about the perfect bullet for deer IMO.