I tried to use Qcharts for some research recently and discovered that the intraday data is way off. I found one minute volumes that were greater than the daily volumes and all sorts of stuff. Changing servers did not fix anything much.
I kept the service because of the wonderful charting package but I had to get another service for doing anything detailed and meaningful.
One thing about Realtick is the the VBA code is exposed for the Excel interface. If you are doing anything in Excel and VBA they make it very easy to start.
Max