Hi Red Stag,
I think the 9,3 FOX 220 grs is, indeed, a do-it-all bullet for medium game! As is the Barnes TTSX 250 grs! I would use either with total confidence ! If you want, or can, use a lead core bonded, to me there are none better than the Nosler Accubond 250 grs! Also love this bullet.
In a good rifle with 60 cm (23,6) barrel, you can get 2750 f/s with the 220 FOX, and 2600 f/s with eiter of the 250 grs. With essentially the same performance on medium game.
If you want to use only one bullet for your Red Deer and African plains game, perhaps I would chose any of the 250 grs. The BC of both is great and compensates for the slightly higher MV of the FOX.
Good luck!
CF