Yes my clouds can move, in lower resolution, after any move is done, the high resolution bakes itself into an half cube (upper sky dome) using tiled rendering.
its too slow for pure real time, it would lower the system to around 1 or 2 FPS in full res full real time.
The biggest issue is the number of times the fractal needs to get evaulated per pixel. knowing the fractal is made by iterating reading a noise texture with UV coords that multiply exponentially (octaves). I calculated that at max quality one pixel = 1800 texture reads. Of course it only works so great because the texture is so small it can get in the cache. But I even suggest using registers (constant buffers) to pass an even smaller noise base, that could help I guess.
Though, in my technique the shader was so complex, on DX9 it was difficult to compile because I would exceed the max number of registers very often.
Because of the presence of loops, and dependence on variables outside the loops, creating arrays with size that multiplies with the nested loops...
Anyways, the night, sunset and dawn are handled with a mix of empirical tunings and the effects from the aerial perspective (rayleigh). The empirical stuff is mainly the intensity of the sun light, and the sky light that I use as a second source from the top. Normally you should evaluate the irradiance of the sky as a 3D function (encoded into spherical harmonics or as an lookupable envmap) but a single scalar is more than enough in the sky case because of its uniformity across the hemisphere.
The quality of the technique is that the light direction change really change the volume impression we get of the clouds. Though it is not using scattering formulas, its already slow enough :) instead it uses empirical formulas.
About the parameters, there are literally tens of them (~50), but I reduced it to 10 "master" parameters that drives the other ones with empirical ramps that I adjusted to be "cute". So the user can move the sun, time of day, or change the quantity of coverage, and it any combination it remains controlled and the best consensus. It took days to adjust.