About the predictive market closing, is there an opportunity or not? hmm.. if u think there is no opportunity, there is no opportunity. If u think there is, then there is. That is how arbitrage works, if everyone thought alike, there would never be any opportunity in the first place.
One of the most important reasons we put this was because of the huge chaos that happens on expiry because of STT. This chaos is even more when markets close at levels like 7801 or 7998, you know very close to popular strike prices. Let me give you a real example.
A few expiry's back, this client had bought 200 lots of I think 7800 or 7700 calls (can't remember which one exact but one of these 7701 760) at Rs 15 around 3.10pm on expiry. The market was on its way down and at 3.25pm Nifty was around 7793, and he thought he has lost the entire Rs 15 and as the market was going to expire below the strike. The weighted average brought the closing up to 7801. So he was in the money by Rs 1, what this meant was that his option got exercised, so he ending up losing around Rs 300/lot as STT, Rs 60,000 in all, which he could have saved if he saw that the predictive closing would be higher than 7800.
As I said they are all small little things, but every such small thing keeps adding to a traders edge to win in the markets.