Not sure what your cashback amount is, so I can't compare that.
Your premium seems to be $1748.08 and there is a ~$80k death benefit, I assume with TPD but no CI. I'm not sure your age, and an Aviva Direct term plan for 20 years from age 40 is about $148/yr, so let's assume that leaves with you $1600 per year to invest for 21 more years after surrendering at year 4 for $3631, and you want to try to beat the non-guaranteed total of $57222. Plugging this into TVM calculator:
So you need to be able to invest with a compounding interest of 3.69% to beat $57222. You can safely achieve that by putting your money into SA (and get tax refunds!). I believe the non-guaranteed amount assumes that the prudential par fund performs at 4.75%. If you can also get 4.75% with STI ETF then $57222 is easily beaten.