3: High voltage has higher loss, but because you will be sending much larger packets of EU, the overall loss will be much less. e.g. batbox sending current to another batbox over 5 cables, that's one loss. Over 32 pulses (for ease of math), you essentially lose one full pulse.
Using an MFE, because the energy is bunched up into larger packets, 2 or 3 loss is much less of an issue (basically, you'll need to have 4 times the loss before you're better off with lower voltage). Similar rules apply to the higher tiers of electricity.
I don't know if I got it, tell me if I'm right:
I have 2 insulated copper cables which are 5 blocks long, If I send through them the same amount of energy (for example 32 EU/t) but in the first cable this power is into only a single packet and in the second one into 16 different packets, at the end of the cables will the first cable have a packet of 31 EU and the second one 16 packets of 1EU?
Is the energy loss calculated on every packet or on the average energy per tick?
I apologize for my English.