HD vs SD in lowlight conditions
 

Hello guys,
theoretically and perhaps thatswhy practically as well is SD in lowlight conditions much more sensitive and gives much less thermal noise than HD. That is because SD-CCD's have bigger pixel which could catch more photons than HD-CCD's. One way is to avoid that lack is to join electronically/logically few neighbour pixels in CCD to enlarge pixels sensitive area.
My question is that is there any HD camera which operates so in SD mode?
And if it's so, is there any advantage because of that?