You might get more responses in the Beginner Question Thread but I don’t think this is the “wrong” place to put this
This thread does a really good job explaining the difference.
The key part is to understand is the relationship between watts, volts and amps
When put into a motor, volts turn into rpm, amps turn into torque and watts are the culmination of both.
An esk8 motor rarely needs to spin at full rpm meaning there’s excess voltage that can be converted to current by the ESC.
At 50% of your boards top speed you’ll only need 50% of your boards battery voltage, meaning you can draw 10a at 50v from the battery and push 20a at 25v to your motors.
Max Regen at -15a will indeed put 15a to your battery, this number is also per motor, meaning with 2 motors you’ll put 30a into your battery.
This is not the same as charging at 30a though, this braking current is made up of spikes of current rather than a consistent 30a. I don’t have any info on pulsed charge limits on A123 cells though.
As long as your motors aren’t overheating you can increase “motor current max brake” If I recall correctly the DV6 can do about 80a/side
Putting more power through anything will indeed stress it more, your DV6 though is rated for quite a bit more than you’re using it for, I wouldn’t worry about raising them unless your motors start to overheat.