I cancelled my MTN contract, and moved my SIM to prepaid. Was planning to buy a Google Pixel and move onto Afrihost. However, with that not materializing, I decided to get a LG V20 instead, which was last week only available on a Vodacom contract.
Moving from contract to prepaid on MTN was not a fun experience, dealing with the call centre. Porting took a few days, but was otherwise a breeze, perhaps because it was from a prepaid SIM.
What did catch me was that ABSA (correctly) flagged my SIM as swapped, and blocked any transactions requiring an OTP. However, that block was not actually lifted after 36 hours like they claimed, and I had to go through the fraud department to get the block lifted again. This is a good initiative IMO.