Here is a breakdown of the light component weight.
Bikeray Speed II (blue light at back of helmet) = 120 gram
Gemini 3 x XML Olympia (grey light at front) = 80 gram
Replay 1080 XD = 85 gram

The total stuff on mt helmet is about 300 to 350 gram including the lights, light holders and wiring. The balance is almost perfect being that the heavier Speed II light is at the back of the helmet and the Olympia at front being the lightest light. This setup is about the same as most single light and battery mounted on the helmet since I do not mount the battery on the helmet.

I run an cable from the back of the helmet to a flat battery pack which I put in my vest pocket. I have one of those Fly Fisherman vest with a gazillion pockets which is perfect for my external pack. I don't use an OEM battery pack since they do not perform that well. I use this semi semi DIY battery pack using this holder and panasonic NCR unprotected 18650. The batteries is capable of providing 3+ amps and so does the holder PCB circuit. The pack allows me to remove the batteries so that I can balance them out which will provide me with consistent performance. I usually just balance them out like every 4 or 5 month or when needed, otherwise I just plug a charger into the pack. I did have to use Trail Tech wiring for the extension and Y adapter since they are the heavier 18ga wire instead of 22 or 24 gauge wiring used by most OEM wire like Magicshine. The lighter wires from Magicshine are too small in size to handle the large current load and the voltage drops too much.

The throw from the Speed II in combo with the flood of the 3 x XML Gemini Olympia is about as good as I can find for the time being. I can use just the helmet setup only if needed since it is so bright off trail but I usually run also a handle bar light like the Gloworm X2 light.