I have had excellent results from Swift A-Frame and Woodleigh for softs from my hunters, so you can't go wrong with any of those two, as been mentioned by a couple of hunters above. I have heard of mixed results from the Hornady Solids, I think they are the DGS, but past that, I think a solid is a solid.
I will still advise that you bring at least some solids. You just never know when you will have a wounded Buff, standing with his head in a bush, only presenting a rear-on shot. Only a solid will have the penetration to get to the vitals from that angle.
Good luck. We look forward to the photos!
Take Care,
Marius Goosen