On the one hand, with another 243 Win you would only have to worry about one type of ammo. The 243 Win is a fine deer cartridge, especially in our neck of the woods. The 243 has a bit less recoil than the 7mm-08 although the 7mm-08 is not a heavy recoiling cartridge as long as the gun isn't too terribly light and the stock fits. The 7mm-08 has better ballistics than the 243 hands down, but dead is dead. The other thing is if you get another 243 they won't be arguing over who gets the 7mm-08.