I got 2 IT and a Frontosa growing out together....so far the bigger IT is the king of the tank. Fronts and Dats grow pretty slowly... so they should grow out well together. I'll probably get another of each.
i have my 8'' ST and a 3-4'' IT in my front tank and the fronts are 4-5'' and have no real issues just a bit of squabbling now and then.
the fronts are tank bred so are fine in my 7.5 Ph tank at the moment although once the fish in the tank are able to be added back into the main tank i will add more fronts to the front tank and it will be back to fronts only and the water will be adjusted.