Ok, so here's the spread:
The "robots" will buy and sell 5000 of these shares at a time, continuously. That means you can do a purchase for +- R142 000 at a time. Once you've done that transaction, give the system a few minutes and you'll see that the robots have replenished themselves back to 5000 again.
The current spread is 20c, meaning you're likely paying a 10c premium over the asset calculated price. That's a percentage of 0.35%. That's more than the STXIND at 0.12%, but less than the RMBMID at 0.61%. One point to note, is that the DIVTRX has a TER of 0.38% against the STXIND of 0.45%, so you will make back that spread fee in about three years, and after that you'll be better off.
Unless something major changes my mind, I'm still planning on switching my purchasing to DIVTRX from next month.