Tell me about Balito, is the city worth a visit?
stop for a couple of days, 1 night might be, stroll around, beautiful, little town, green. I would consider stopping in Ballito on the way back from Saint Lucia, have lunch, explore, drive around the city, take a walk on the beach, there you can decide whether to stay overnight. Durban will be more interesting and farther coastal towns.
If you're interested in a hiking trail in Hluhluwe with a guide, there is a famous guide named Nunu who works at Rhino Ridge safari lodge and also independently.
It is highly doubtful to prefer Durban for a vacation over Ballito. In Ballito, a great promenade has been built, it's very quiet and peaceful, and there are swimming pools available; in Durban, during the season, there will be no place to stand by the ocean.