I have looked at the Sabi while in So. Africa..See little reason to opt for it over a factory available 338-06..In 338 my choice is the .338 Win. as the action is std. length, it outperforms all the mentioned above calibers with a 210 Nosler at 3005 FPS and a 300 gr. Woodleigh at 2500 FPS..you can't beat that for and all around caliber..

By the same token I see the 30-06 with a 180 or 200 gr. nosler at 2700 FPS an excellent plainsgame caliber. Hard to beat indeed.
I am not particularly a caliber buff per sey, rather a beliver in a properly constructed bullet for the game I'm shooting and placing that bullet in the right spot is utmost.