I fully concur with Andy, I have had several 6mm-284s and the increase is very significant, you will get virtually no increase with the AI as the 243 already has a relatively steep shoulder and little case taper. The 6-284 is a whole new ball game as 6mms go and I highly recommend this conversion. I have taken several head of medium sized game with 95 gn Parts from my 6-284s and they kill like lightening, it is a sight to behold watching a caribou fold up to that little bullet. And let me tell you any one who has shot a lot of caribou will tell you they are just not subject to shock like a lot of similar sized ungulates. I love the 6mm-284, almost as much as I love 243s............and have not been without one for decades.
Dave, I agree to a point, however to really use the case capacity one really needs a long action with the 6mm Rem. I had a 6mm AI once upon a time I got from Ted, in a 98 action and it was impressive as well but not so much in a short action, this is where the 6-284 really shines.