If you have a full day at Vic Falls, that is probably enough. I would go two days in Capetown and use the extra two days to see the Delta and Sabi Sands.

Having been to both the Sabi Sand area and the Delta, I agree with your friend's assessment that the Delta (and Botswana) has more of the romantic, Out of Africa, feel. You are so much more remote! The combination of both is perfect and you will see the big 5 AND the wonderful birds and smaller critters that Africa has to offer.

Here is the luxury itinerary that we were very happy with...

- Singita (Sabi Sand, lodge with AC)
3 nights

- King's Pool (Botswana Linyanti, tented camp)
2 nights

- Jao (Botswana Delta, tented camp)
2 nights