The problem as a trader, is your levels and stops are based on actual real prices from the exchange. To the degree that IG's Australia 200 cash reflects the same levels within a few points, everything is fine. Where they differ significantly, makes any levels for entry, stops, TP and chart retracement levels pointless.
IG's Australia 200 cash differs from the actual index now by 18-19 points currently.
It appears to me that IG is pricing the cash index off some fair value calculation, but on this I am not certain.