Unfortunately I no longer have 1.0 installed on my machine, but to get the trigger working incorrectly with 1.1, you need to set the time as well as configure the trigger. Since the trigger is configured based off a given start time, it is important to zero out the time value of the onboard device timer. If you don't do this, there is a possibility that it will not start at zero and the value that you specify for the start trigger time may have already passed. Here is a screen shot of how to set this up:
As I mentioned, I don't currently have a system to check how the trigger was set up before, but using these 2 VIs you should take care of the error. If you are still having issues let me know and I'd be happy to help.
As to what changes were made, I cannot give a good answer. However, I do have a work around.
If you look in the NI-USRP Help document, there is section called Data Streaming Performance Tips. To get back to the rates that you saw with the 1.0 driver (and better based on benchmarking tests I have run), you will have to make a change to one of your registry keys, FastSendDatagramThreshold. You will need to change this value to greater than 1500. I set mine to 2048 and had good results. The help document has more details about how to change this registry key.