We have just had a flurry of discussion in here about stators, regulators batteries......and all of the problems seemed to steer toward the connector from the stator to the regulators. Start with checking it to see if it failed and allowed the battery to discharge.
Another thing may be oil level. If the oil level gets to low, it causes the stator to overheat and this would result in low output and eventually failure, but you said that all that was fine. You may need to check that your cooling system is working properly.....the fan and the flow of the coolant. I would tend to think if you were moving at 60mph that the fan not coming on would not really allow you to overheat until you came to a stop.
Check that connector first and then pull it appart to see if any of the phases are shorted together.
96-VT1100C (other bike is an '81 kaw KZ)- I am not required to know everything....I am only required to understand what I know...