Previously, in IC(1) HV was used to reduce the number of times the distance loss was applied to transmitted power by compacting it into packets, however the new wiring system has changed this, and it has made HV useless!
Lets imagine you have a power generation area 100 blocks from where you need power. To make the power line out of HV4x, we would need about 25 pieces of refiron, as well as 300 rubber! To make it out of glass fiber cable, we would need 5 diamonds, and some readily available glass and redstone. This doesn't look too good for our power line...
But what about energy loss? Well it seems that the HV cable would lose 80 eu/t. Thats the equivalent of 80 solar panels. Absurd! It looks like using HV cable (ironically) won't be good for transmitting our power via HV.
How about glass? Well that would lose only 5 eu/t (wiki says .05, while Al's post says .025, I followed the wiki). Thats reasonable, though it would require 5 precious diamonds.
So it seems niether HV capable wiring is great. HV4x itself is miserably expensive, as well as being horrible at conducting energy, so it's use is pretty much limited to very short distance transfers between MFS units and such. As for glass, its not too bad, but the usage of precious diamonds for it is quite a deterrent for non-mega-rich players.
So in conclusion, HV will either be horribly horribly expensive, or horribly horribly wasteful, and it would just be a better idea to move your power station closer!
Does anyone else find this wrong? Central power should not be a thing of the past, but it seems it simply isn't possible. What's the point of cables if we can't use them for more than a few blocks length?