So I was considering the benefits and limitations of FDM/SLA etc. SLA trounces FDM in resolution but lacks in strength and is expensive in consumables (resin etc). I rather like the benefits of FDM though. I started thinking of ways of making FDM better. Resolution is improved with smaller nozzle diameters and layer heights, but that makes print speed unreasonably slow. I think as long as we're sticking with shoving hot plastic through a hole, in order to get the best of both worlds, the real answer is an adjustable hole! Consider a nozzle tip that can be changed with G-code from .2 to .8 in real time mid print. Crush your infill and interior aspects in .8, do your perimeter in .2. Variable layer height isn't a problem, especially if the two are divisible, ie .1 on the outside .3 on the inside, three layers around the outside for each internal lap around the print bed. You'd have to modify a slicer to support a new command for adjusting such a thing, but I'd imagine DC42 or one of the other geniuses could handle that. The hardware shouldn't be THAT hard to figure out, although I concede I have thought of a few rough methods but haven't really flushed them out in my head.
I would have thought a variable nozzle size would be an expensive solution. Why not use two extruders of different sizes. You can use a different extruder in Simplify 3D for Layer and Infill. I don't think you can have different heights, but you can certainly have different widths.