To be honest stopping with Poser isn't the question here. Poser has some features you will not find in any other application, so look most likely will continue to use it even when you change your rendering solution. A lot of people get better (and faster) results using other renderers, so that will always be a possible solution.

Your problem is that you assume you will get a realistic looking render if you apply realistic lights to a realistic model. This is NOT the case. Even when you make a photograph you will generally add a few fill lights so the photo will look more realistic. Remember you look a picture as a single object while in real 3D space your eyes automatically adapt when you change your focus. A photo fill light uses real light while a render uses simulated lights, due to the shortcomings of the simulation even more fill lights are required and the special features of simulated lights can be used to your advantage.

Throw in a few extra low intensity lights and your render times will come down a lot for better looking results. Realistic looking scenes is in the eye of the beholder. Simply cheat.