Playing around with the vanilla Redstone Comparator and Alloy Wire, it seems like that the Alloy Wire doesn't light up when the redstone signal is very weak.

In the below image, the redstone comparator has a strength of 15 coming from the back, 14 from the side. So the result is a signal strength of 1.

The redstone wire on the right is lit up with that resulting signal strength. The Alloy Wire however does not light up, but has the same strength. The lamps in the image are Inverted Black Lamps.

Minecraft 1.7.10
Project Red 1.7.10-4.5.1.51
Direwolf20 Pack 1.7 version 1.0.2

It does, its just very weak so its hard to tell. Inputting a 1 signal means that the wire has a signal of 15/255, that means there are 255 different shades of red the wire could be lit up in, 1 being the darkest and 255 being the brightest. 15 is very hard to distinguish between zero, but it does light up, and you can see it if you look very carefully.

Ah, okay.