Today I got word that Vodafone UK has pricing for the the 9780 so it would seem that they are close to releasing these device. Usually US carriers are around the same time so we should probably see AT&T and T-mobile release it soon. With the 9780 having similar specs as the 9700 except for better camera and memory I expect it to do rather well. We got a chance to play with a 9700 running BB 6 at DEVCON and I have to say it runs really smooth so it should run great on the 9780.
Here is some pricing information for plans and you get the device free with the plan.
900 minutes (anytime/network)
500mb of data
£35/pm (24 months)
£40/pm (18 months)
So are you thinking of buying a 9780? The 9700 is a great device and with more memory and the battery life I expect the 9780 to be the same but better. If that is the case then I think it should do well when it launches. This device is expected to launch around November if not earlier.