did some tests yesterday evening. the problem with low sampling is only if you use values which are to high. for example i used a light thats half of sun in intensity in a small room without gi and mat with 0.25 for glossiness. then you need alot samples in the shader to resolve that. but if you use normal lightintensitys like 4400lm (its a high intensity for normal lights) you will get no problems. i think intensitys like 20000lm should work without problems.