Barrel length, Barrel length
I hunt Deer in MN. If you are hunting in the woods then where we hunt looks about the same. A long shot where I hunt is probibly 75 yards, with most shots being around 50 yards. The 30-06 will usually have a 22 inch barrel, the 7mm Mag will usually have a 24 inch barrel. This makes a big difference in thick woods getting to where you are going to set up for your hunt. If you are hunting Wyoming Anelope at 350 yards I would say that it makes sense to carry the fast magnum. For mid west hunting I don't see the fast magnums having usable advantages. You also stated that this rifle is alot heavier than your last. A really smart writter once wrote this, and this has been often repeated "The single most thing we all do with our rifles is to carry them". I personally like my rifle to weight around 7 pounds before I place a scope on it. Then the total with rifle, scope mounts/rings, scope, sling, and full magazine is around 8 pounds. A little lighter is better just don't make it to light unless it is a light recoiling cartridge like your old 7mm-08. Most gun shops won't let you return your rifle for full credit, if yours does that is great. I know of one guy who took his family to Africa, his wife and younger son carried bolt actions in 7mm-08. They both took several plains animals each using their rifles and were not under guned.