I flew DD with 2s lipos for a couple months. I have two of the small blade heat sinks on my tail motor. When I switched to 3s last month, the only change I made was to the 8t pinion. The biggest benefit I've seen is the extra weight of the 3s adds a lower balance to the frame which seems to give me more control. The added head speed combined with the weight was a huge improvement. It's like having the training gear on for weight. It's very stable now.

Water break-in is the process of hooking the motor to a 1.5 volt battery and dropping it in a glass of water (just the motor). What it does is shape the brushes to the armature which increases efficiency. The purpose of the water is to wash out the residue from the brush wearing away as it takes shape. Getting the dust out of the motor. Without the "bath" the brushes will still wear in, but they have to fight that dust all the time and it can actually put grooves in the armature. Make sure you run the motor after taking it out of the water and lightly oil the shaft. Be sure not to get any oil in the motor. I do this with all my brushed motors before I put them into service. I didn't with my first heli and lost two tail motors in two weeks. I have not burned out a motor since (fingers crossed)