Update: Thank you all for your comments. They are very helpful. I have not done a couple of "high cadence" rides. It is definitely a different work out and will take some getting used to. Last night's ride (30 minutes/7 1/2miles) compared to the same ride a week ago when I was riding "normally", my cadence moved from 62rpm to 73rpm. My speed was virtually the same but a little slower actually (14.8mph down to 14.6mph). My hard beat was up 10 beats/minute and I burned about 10% more calories. So that speed did not benefit from this and I can't tell yet about improved endurance because the change is still pretty significant for me that I will need to give it a few weeks or more for my body to adjust to it. To me it is just a different kind of challenging. I was surprised at how much more gear changing I had to do to keep the cadence up. There is nothing wrong with changing gears a lot but given that I ride on rolling hills I have to really watch the cadence monitor and change the gears a lot. I am sure that when I get more experience and get used to it I will be doing that without much thought but for now it is a very different ride.
Thanks every one for your help.