I love my H501w, but I have to say that the runtime has been kind of a disappointment for me. Since it's a flood light, I often run it on medium or high where with any of my other lights low or even moon-mode would have been sufficient. Because of this, I find that I need to change the cells at least twice as often as my other lights.
It's an awesome little light, but in a situation where runtime is paramount, it can't compete with something like the Ra or Quark.
Do your RA and Quark use single AA battery? If they use high capacity batteries, shouldn't they be compared to lights that use the same batteries, for run time?