I ran with the same four AA Duracells in my DX3R all last race season. They showed 6V for the first couple weekends and then showed between 5.8/5.5 for the longest time. I still have them in the radio and just used it today, they are now at 4.8. Time for a new set. I got Sanyo 2700 mah nimh cells to use for this race season.
I agree that you will, I was just stating that the DX3R is not power hungry and 4 AAs last a long time. But if you use your RC a lot and for long periods of time then go ahead with the lipo upgrade. Be sure to post pics of your set up.