I'm in the process of converting over to bare bottom. I've pulled out all the sand in my tank and sump refugium, and I've jumped on the 'cooking' live rock band wagon as well.
The amount of waste material that has accumulated in the tank and sump after only a month is an eye opener. I cannot imagine the biological processes in a 50-gallon tank could keeping up with that for very long.
By going bare bottom, I'm hoping to make the waste products easier to remove, and to avoid sand shifting/agitation issues caused by my closed loop.