I just don't see what is so great about a 243. A 100gr bullet at 2900fps is not fast by modern standards. The 243 isn't even the fastest 6mm on the market. The 6mm Rem will push a 100gr bullet over 3000fps so I guess that means that it's a little better than the now sainted 243. I'm sure some Weatherby guy has a 240 Wby that probably pushes or passes the 3400fps mark.
Numbers from a ballistic chart, wether its fps, sd, bc or any other number you want to use is only a starting point. All of them plus the shooters ability to place the bullet on target are required to have success. A person needs first hand experiance and confidence in want he uses to be an effective hunter.
If speed alone is the greatest measure of effectiveness then why doesn't everyone use a 240 Weatherby or a 220 Swift since nothing bigger than a 6mm bullet should be used for deer hunting.