Here is an update on the situation.
I've updated everything to the 1.3 stack and am getting better results.
I can achieve frequencies of 30 Hz reliably.
40Hz is unreliable, it works for the first few seconds and then will start to have a lower and lower rate in which notifications are being received. If I power down the transmitting device, btool would continue to show many notifications.
I suppose Matthew Kendall is right and that this is a limit of the dongle. I am fairly certain that this is not a problem with btool because I have my own program to parse the received notifications and am getting similar results.
Can I check whether the HostTestApp project that is given is actually the firmware that is loaded onto the usb dongle? I might take a look at it when I have time to see if there is anything that could be done to boost the notification rate.
