Let me give you some insight from one who has actually travelled on SAA's 346. The seats are tight, there's no denying that. Usually the buklhead row gives more legroom but the seatbelts have airbags in which are awful.
The best block of seats (I don't know how many you are) is 45 DEFG on the overwing exit row. Good legroom and no airbag. The AC
seats in the same row have airbags.
Best seat in the house for a single traveller is 74D as it has double legroom.
SAA are repitching the economy seats on all their aircraft this year but there's been no indication of when each plane will be finished.
Other than that the 346 is a great plane to fly on, IFE is AVOD and has always worked fine when I have flown. Each seat has a game controller handset and a phone.
Another alternative is to go via LHR
and get an SAA 744 to JNB
, upper deck is economy and the seat pitch is 34", better than main deck. IFE is also AVOD.
After Monday and Tuesday even the calendar says WTF...