ashley.. it's all about what you want to get out of your renders.  you hit the nail on the head for some people.  what is it worth to you to increase the quality of your renders.  i spent years working with poser before switching over to daz studio for a variety of reasons.  i've had some firefly renders go overnight also.  i'd say that if a ff render is only taking you 20 minutes, then there's absolutely no comparison to that final product and a 5hr lux produced render.  once again, it all depends on what you're looking to get out of your renders.  myself, i try to get the maximum amount of realism that my skills and tools will produce.  being that i don't want to muck around hacking lux's files manually, reality is the way i go at that.  i've, also, seen octane renders that approach(and sometimes surpass) what the reality/lux combo can produce; but the price point for that is beyond my means.  myself, i'm looking to see what some of my favorite poser artists can do when they try out reality and luxrender.