Well, I for one am pondering this bullet question.
I am booked to hunt buff & plains game (in that order) in Zim next August with John Sharpe. I posed this question to John at DSC in January, and he is adamant about me using 300 gr A-frames for buff when I hunt with him next year. He's still not persuaded the 270 gr TSX's are as good. Others whose opinions & experience I respect have said they would rather use 270 gr TSX's, and I'm mightily persuaded, but bottom line, I'm gonna have to go with John's choice.