A pity all the former modders of Arcs are apparently quiet. I mod my own, but I'm not ready to be in business.
To anyone with a little experience on LS's, the biggest problem is getting the retaining ring out. Sometimes it come right out, sometimes it's huge problem and you have to grind the ring out and replace it. After that, any changes are really simple. A current boost is a simple resistor addition. The Luxeon is simple desolder/resolder. Changing the optic for a reflector is a few seconds work. However, this assumes one has all the replacement parts - decent LuxIII, spare resistors, reflector, and surface mount soldering equipment and skills. As long as you're in there, you may as well change stuff to what you think you want, if you want.
And my understanding is that the orignal Arc LS boards are not recommended for unregulated (i.e. 4.2 volt) LiIon, as any battery voltage over the Vf of the LED will put the light into direct drive mode.