I kind of went a different route when building my V2.
I used 5 conductor #20 ribbon cables made for RGBW LED strands, and ran the flat ribbon cable up the side slots of the extrusion verticals pulled tight and behind the T-nuts.
http://www.amazon.com/gp/product/B00NANLXNC
I used one 5 conductor wire for the endstops (Black and Red were GND and 5V(or 3.3V in my RADDS system), then White, Blue, and Green were the sense return lines for the endstops). I wired all endstops in 3 wire config for positive assertion of both states to prevent EMI/RFI from floating Normally Open switch style connections. I'm using RADDS with an Arduino Due, running Repetier firmware.
I too had some stranded #20 4 wire signal cable (used in alarm sytems) that I used specifically for the extruder stepper motor that ran down the center hole of the extrusion.
For the extruder heaters, fans, and thermistor, I ran another 5 wire #20 flat ribbon cable and a 2 wire #20 cable together up the other tower and down to the head terminated in 5.08mm spacing bard style screw terminals soldered with heatshrink.
On that one, I use white/blue for thermistor, then the main single separate 2 wire #20 was for the heater, then the Red of the 5 wire was for fans. That leaves black and green as returns for a hotend and a print cooling blower fan. This allows you to run 24v heater and 12V fans, or just not have a drop in fan speed when the heater kicks in.
Finally, for top mounted LEDS, I ran 2 wire #20 down the center hole of a open extrusion for constant on 12V LED strips.
The reason for all this is:
#1, I was scratch building a custom V2 and didn't have a kit wiring
#2 The 5 wire ribbon and my standardization of color schemes and functions across my printers that I custom build keeps wiring tidy and organized.
#3, by not ramming a bunch of wires down a round hole in the extrusion, I'm less likely to cut the insulation and short, but also, I gain some EMI/RFI immunity in how I placed signals and known EMI producing wires. Specifically, the extruder stepper is both a twisted 4 pair, but also inside the central bore of aluminum. No other signal wires (endstop or thermistor) are in that tower, let alone running next to the stepper wires.
This methods made for a faster build, less soldering and points of failure, and a cleaner easier look.
#4, the wires to the hotend are contiguous all the way from the mainboard to the hotend with no splices or solder joints. The routing is clean and sharp bend free, the exposed loop down to the hotend is covered in black mesh which helps limit bend radius and looks sharp.
#5 the screw terminal termination at the hotend makes swaps, repairs, testing, and just assembly a joy rather than a nightmare. It's might not be the plug and play of the Eris, but it's not that far off either.
X tower
5 wire cable for endstops run down the side.
Center hole is open for another wire run should I need it.
Y tower
Side is both a 5 wire and a 2 wire in the V of the side where the rollers go. This is the contiguous wire run to the hotend. Has thermistor, 2 fans, extruder heater. If you wanted to be extra slick, I could use the heater power and then use the second red for a constant on source (say LEDs strips on the effector). As is, the hotend fan is temp controlled in repetier. The instant the heater turns on, it's on and stays on until the hotend is below 50C. As such, I wired in LEDS in parallel to the fan, such that the LEDS are effectively on the instant you call for heat, and don't turn off until well after a print finished and the head cooled to less than 50C.
Center bore of extrusion has a 2 wire #20 for 12v leds and general 12v power (say you wanted a fan on the extruder feeder motor)
Z tower
4 wire #20 for extruder stepper, terminates in screw terminals for easy motor swaps.