Happy to see polygon.io data is possible to use now, will start testing this.
Is adjustment for corporate events, dividends and splits handle in same way in platform as IQ.Dtn ?
We have our own service for corporate event factors which adjust data for both splits and dividends. Historical data is backtested on adjusted data (unless you turn this off completely from the Options window). If you need to access both adjusted and unadjusted data from your script then we offer a function called DataSplitsDividendsAdjusted, which you can call to switch between the two during runtime. So scripts can access adjusted and unadjusted data while backtesting calculations are all done on adjusted data.
Our factors take into consideration both splits and dividends and we apply them on data that is unadjusted. DTN IQFeed adjusts its daily data but does not adjust its minute bars. I believe we apply adjustments to their minutes data during backtesting, same as we apply to Polygon.io's data and our own Tickblaze equities data.
We do not use the Polygon.io option to have the data they deliver to be adjusted only for splits, as that would not work well with our existing architecture. If we ever decide to add only split adjustments or only dividend adjustments then it will be implemented on our end for all vendors.