I would consider blowing up an MFSU or frying a glass-fibre cable to be a swell personal achievement, so I tested in a creative world to see if it's actually possible. I hooked up a load of HV solar arrays (producing 512 EU/t each) to an MFSU with GF cables, and according to an EU-reader about 11k EU/t was flowing, and it was all still working. What gives?
As I understand it, in the old power system, energy was sent in packets, and you could send as many packets as you wanted as fast as you wanted, so long as they were small enough not to overload your machine. I was under the impression that now the energy fills the grid and two batboxes outputting to the same wire would count as 64 EU/t and would therefore blow up, say, a Macerator. *checks* Nope, didn't blow up.