Very nice. The new D-series servos are great. I've recently equipped another plane with a set. They seem a bit smoother and quieter then their predecessor, which was the 5645 digitals... and the D-series are HV compatible... which doesn't mean you have to use an HV(7.4v) battery, but the option is there if you want it. In the case you dropped down to a 6.6v LiFe, you would lose some torque (
[email protected] vs
[email protected]), you'd be down about 22oz comparitively, and a tad slower. I would say go for the HV option in that plane if you can. The servos will be faster and stronger.