I can't speak about bogger boxes from personal experience (I use Reos), but I heard they're very well built.
Learning curve -- yes, there is one. In the beginning, I found it extremely frustrating to use atomizers. I either flooded or dry hit them, so I used cartos. Cartos taste better on a bottom feeder than they do by themselves or in a tank, likely, due to the juice being fed directly onto the coil.
With rebuildables, the learning curve is different. If you're already used to dripping with a particular atomizer, bottom feeding it is about the same as dripping. And ERA is a very fine choice.
So far, the simplest to setup, and the best overall BF RBA that I came accross is the reomizer 2, with ERA following a very close second.